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 A088593 #13 Aug 27 2022 08:14:06 %S A088593 18,55,83,125,47,71,107,161,121,91,137,103,155,233,175,263,395,593, %T A088593 445,167,251,377,283,425,319,479,719,1079,1619,2429,911,1367,2051, %U A088593 3077,577,433,325,61,23,35,53,5,1 %N A088593 a(0)=18; a(n+1) = largest odd factor of 3*a(n)+1; stop when a(n)=1. %C A088593 Similar to a Collatz sequence. %F A088593 a(n+1) = A000265(3*a(n)+1). - _Michel Marcus_, Aug 23 2022 %e A088593 a(4)=47 because (a(3)*3+1)/2^3 = 47. %o A088593 (PARI) f(n) = n >> valuation(n, 2); \\ A000265 %o A088593 lista(nn) = my(list=List(), x = 18, i=0); while (1, listput(list, x); x = f(3*x+1); i++; if (i>100, break)); Vec(list); \\ _Michel Marcus_, Aug 23 2022 %Y A088593 Cf. A000265. %K A088593 easy,nonn,fini,full %O A088593 0,1 %A A088593 Mitch Cervinka (puritan(AT)planetkc.com), Nov 20 2003 %E A088593 Edited by _Don Reble_, Nov 08 2005 %E A088593 Corrected by _Doug Unger_, Aug 26 2022