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 A268708 #12 Feb 13 2016 23:17:20 %S A268708 0,1,1,2,2,3,3,3,3,4,4,4,4,4,4,5,5,6,6,6,7,7,7,7,8,8,8,8,8,8,9,9,9,9, %T A268708 10,10,10,10,10,11,11,11,11,11,11,12,12,12,12,12,12,13,13,13,13,13,13, %U A268708 14,14,14,14,14,14,15,15,15,15,15,16,16,16,16,16,16,16,17,17,17,17,17,17,17,17,18 %N A268708 Number of iterations of A268395 needed to reach zero: a(0) = 0, for n >= 1, a(n) = 1 + a(A268395(n)). %C A268708 Set k = n, take the k-th Xfactorial A048631(k) and find what is the maximum exponent h so that polynomial (X+1)^h still divides it (over GF(2), this can be computed with A268389, maybe also more directly). Set this h as a new value of k, and repeat. a(n) tells how many steps are needed before zero is reached. %C A268708 Note that so far it is just an empirical observation that A268672(n) > 0 for all n > 0. %H A268708 Antti Karttunen, <a href="/A268708/b268708.txt">Table of n, a(n) for n = 0..65537</a> %F A268708 a(0) = 0, for n >= 1, a(n) = 1 + a(A268395(n)). %o A268708 (Scheme, with memoization-macro definec) %o A268708 (definec (A268708 n) (if (zero? n) 0 (+ 1 (A268708 (A268395 n))))) %Y A268708 Cf. A048631, A268389, A268395, A268672. %Y A268708 Cf. also A268709, A268710. %K A268708 nonn %O A268708 0,4 %A A268708 _Antti Karttunen_, Feb 11 2016