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 A344229 #26 May 11 2024 21:54:59 %S A344229 1,2,6,21,85,430,2586,18109,144873,1303866,13038670,143425381, %T A344229 1721104573,22374359462,313241032482,4698615487245,75177847795921, %U A344229 1278023412530674,23004421425552150,437084007085490869,8741680141709817381,183575282975906165022 %N A344229 a(n) = n*a(n-1) + n^signum(n mod 4), a(0) = 1. %C A344229 This sequence is one of many possible solutions to puzzle 16 on the Meerdaelquiz puzzle page, cf. the Delestinne link and A090805. %H A344229 Alois P. Heinz, <a href="/A344229/b344229.txt">Table of n, a(n) for n = 0..450</a> %H A344229 Hugo Delestinne, <a href="http://users.skynet.be/lch/mquiz/mquiz%202003/vragen/mquiz_2003_tafelronde_2.htm">Meerdaelquiz</a> [broken link] %H A344229 N. J. A. Sloane and Brady Haran, <a href="https://www.youtube.com/watch?v=0zT16q3p24M">A Sequence with a Mistake</a>, Numberphile video (2021) %p A344229 a:= proc(n) a(n):= n*a(n-1) + n^signum(n mod 4) end: a(0):= 1: %p A344229 seq(a(n), n=0..23); %Y A344229 Cf. A000142, A000522, A010873, A033540, A053817, A057427, A090805, A166486, A277506. %K A344229 nonn %O A344229 0,2 %A A344229 _Alois P. Heinz_, May 12 2021