This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A272699 #15 Jun 28 2025 16:16:48 %S A272699 2,7,5,3,7,5,5,2,7,5,2,7,5,2,2,5,2,2,7,5,2,7,5,3,7,7,3,2,7,5,3,7,5,5, %T A272699 2,5,5,2,7,5,2,2,5,3,2,7,5,2,7,7,3,7,7,5,2,7,5,3,7,5,5,2,5,5,2,2,5,2, %U A272699 2,7,3,2,7,5,3,7,7,3,7,7,5,2,7,5,5,2,5,5,2 %N A272699 Day of the week of Rosh Hashanah in Hebrew year n. %C A272699 Rosh Hashanah, the new year of the Hebrew Calendar, is the first day of the month of Tishri, which typically falls around the September equinox. %C A272699 The holiday of Rosh Hashanah lasts for two days; this sequence considers only the first day. %C A272699 The mathematical rules for determining the Hebrew Calendar stipulate that Rosh Hashanah cannot fall on Sunday, Wednesday, or Friday. So, every number in this sequence is 2, 3, 5, or 7. %C A272699 The Hebrew Calendar is periodic with a period of 689472 years, so this sequence is periodic with period 689472. %H A272699 Nathan Fox, <a href="/A272699/b272699.txt">Table of n, a(n) for n = 1..10000</a> %H A272699 Wikibooks, <a href="https://en.wikibooks.org/wiki/Mathematics_of_the_Jewish_Calendar">Mathematics of the Jewish Calendar</a>. %H A272699 D. Zeilberger, <a href="http://www.math.rutgers.edu/~zeilberg/tokhniot/LUACH">Maple program to determine Hebrew dates</a>; <a href="/A272699/a272699.txt">Local copy</a> %e A272699 Rosh Hashanah 5776 fell on Monday, Sep 14 2015, so a(5776)=2. %Y A272699 Cf. A057349, A057350. %K A272699 nonn %O A272699 1,1 %A A272699 _Nathan Fox_, May 04 2016