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 A231717 #12 Nov 23 2013 19:47:58 %S A231717 0,1,2,2,3,3,3,3,1,6,3,3,3,2,1,6,2,3,1,3,5,3,1,3,6,2,2,3,10,3,3,3,2,1, %T A231717 6,2,3,1,3,5,3,1,3,6,2,1,3,5,5,3,10,2,3,1,3,5,3,1,3,6,2,1,2,4,2,4,5,3, %U A231717 3,9,3,1,3,6,2,1,2,4,2,4,5,3,2,4,3,10 %N A231717 After a(0)=0, a(n) = A231713(A219666(n),A219666(n-1)). %C A231717 For all n, a(A226061(n+1)) = A232095(n). This works because at the positions given by each x=A226061(n+1), it holds that A219666(x) = (n+1)!-1, which has a factorial base representation (A007623) of (n,n-1,n-2,...,3,2,1) whose digit sum (A034968) is the n-th triangular number, A000217(n). This in turn is always a new record as at those points, in each significant digit position so far employed, a maximal digit value (for factorial number system) is used, and thus the preceding term, A219666(x-1) cannot have any larger digits in its factorial base representation, and so the differences between their digits (in matching positions) are all nonnegative. %H A231717 Antti Karttunen, <a href="/A231717/b231717.txt">Table of n, a(n) for n = 0..3149</a> %F A231717 a(0)=0, and for n>=1, a(n) = A231713(A219666(n),A219666(n-1)). %o A231717 (Scheme) %o A231717 (define (A231717 n) (if (zero? n) n (A231713bi (A219666 n) (A219666 (- n 1))))) %Y A231717 A231718 gives the positions of ones. %Y A231717 Cf. also A230410, A231719, A232095. %K A231717 nonn %O A231717 0,3 %A A231717 _Antti Karttunen_, Nov 12 2013