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 A278519 #8 Nov 29 2016 22:40:02 %S A278519 0,3,7,8,11,15,17,19,23,24,28,31,33,35,39,42,44,47,48,51,55,57,60,63, %T A278519 66,69,71,73,76,79,80,83,87,89,92,95,97,99,103,105,108,112,115,119, %U A278519 120,124,127,129,132,135,138,141,143,145,147,151,154,156,159,161,163,167,168,171,175,177,179,183,186,189,192,195,199,201 %N A278519 a(n) = largest k for which A260731(k) = n. %H A278519 Antti Karttunen, <a href="/A278519/b278519.txt">Table of n, a(n) for n = 0..11363</a> %F A278519 a(0) = 0; for n > 0, a(n) = A278517(1+n)-1. %F A278519 For all n >= 0, A260731(a(n)) = n. %o A278519 (Scheme) (define (A278519 n) (if (zero? n) n (+ -1 (A278517 (+ 1 n))))) %Y A278519 Cf. A260731 (a left inverse), A278517, A278518 (first differences, after its initial 1), A278522. %K A278519 nonn %O A278519 0,2 %A A278519 _Antti Karttunen_, Nov 28 2016