The name Sebastian in Hebrew letters is סבסטיאן. Below: how its number adds up, which page of the Torah it falls on and what verse stands there. Everything is computed, nothing is guessed.
סבסטיאן
In short
Your name in Hebrew letters is סבסטיאן. From Latin Sebastianus, “man from Sebaste”. The city's name comes from the Greek word sebastos, “venerable”. In Hebrew it is written by sound. Adding up the numbers of its letters gives 192 — the same as the Torah word קבץ, “to gather”. That number points to Torah page 192 of 354 — in the portion Metzora. What that portion is about: Purification from tzaraat: two birds, cedar and hyssop; tzaraat of houses; discharges and purification. The verse that begins with the first letter of your name and ends with the last is Joshua 12:2. Each of these steps is laid out below with its sources. Every figure can be checked by hand.
You wrote “Sebastian” — this exact spelling is what was calculated: סבסטיאן. A name from the Tanakh — its Tanakh spelling is used. If your name is spelled differently, correct the Hebrew spelling and the report is recomputed.
Adding up the letters of the name סבסטיאן gives 192.
192
The number 192 is the Torah word קבץ — «to gather» (Genesis 41:35).
And whosoever toucheth his bed shall wash his clothes, and bathe himself in water, and be unclean until the even.
This is from the portion Metzora. What it is about: Purification from tzaraat: two birds, cedar and hyssop; tzaraat of houses; discharges and purification.
Other ways of counting
The tradition counts the same name in several ways. The main one is above: each letter is its number. The other eight are old and checkable too; each gives its own number, and many of them have a Torah word with the same number.
Final letters as 500–900 (mispar gadol) — 842.
Reduced, each letter to one digit (mispar katan) — 30. A Torah word with the same number is כי — “for, because, that” (Genesis 1:4).
Ordinal: alef 1, bet 2 … tav 22 (mispar siduri) — 66. A Torah word with the same number is כמו — “like, as” (Genesis 19:15).
Cumulative: a letter plus all letters before it (mispar kidmi) — 809. A Torah word with the same number is תבואת — “produce of” (Leviticus 23:39).
Squares of the letter values (mispar perati) — 9886.
Building: the sum grows with each letter (mispar bone’eh) — 850. A Torah word with the same number is תכלת — “blue wool” (Exodus 25:4).
The letters that come out are חשחנמתט — not a word that stands in the Pentateuch. Atbash: letters mirrored, alef for tav, bet for shin, and the number of the resulting word — 815. A Torah word with the same number is תבואתו — “its produce” (Leviticus 19:25).
Filling: the names of the letters are counted — alef, bet, gimel… (milui) — 1308.
The number 192 appears in the classical books 1 time across 1 work. The earliest mention is ספר קרניים (~1400).
Every letter of the name explained, the words and namesakes with references, the Hebrew date, the letter and tribe of the month, day 861 of your life (±1), the psalm by age, the attestations from the classical books — a PDF sent to your email.
The number of the day, every morning
Every date has a number too. Once a year it will match the number of your name — 192. The channel posts one number a day, one verse and the Torah page it lands on. Nothing after it, no mailing list.
Hebrew is written from right to left. סבסטיאן has 7 letters: ס Samekh, ב Bet, ס Samekh, ט Tet, י Yod, א Alef, ן final Nun. The first letter is Samekh, the last is final Nun.
For an engraving, a sign or a tattoo, show the spelling to someone who reads Hebrew: transliterating a name is a choice, not the only option.
The name סבסטיאן does not stand as a word in the Pentateuch — as with most names, including many Tanakh names from the later books.
The verse of your name
The Pentateuch has no verse that begins with ס and ends with נ. The custom allows the whole Tanakh — the Prophets and the Writings have 2 such verses. The first of them is Joshua 12:2:
סיחון מלך האמרי היושב בחשבון משל מערוער אשר על שפת נחל ארנון ותוך הנחל וחצי הגלעד ועד יבק הנחל גבול בני עמון
Any name written in Hebrew letters is a number: סבסטיאן = 192. And every date has a number of its own. There is a day in the year when the two coincide.
Each Hebrew letter has a number; a word's number is their sum (alef 1 … tav 400). The page is the remainder modulo 354: the Torah divided into 354 pages of 861 letters, as the lunar year has 354 days. Everything can be checked by hand.