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 A278517 #8 Nov 29 2016 22:39:49 %S A278517 0,1,4,8,9,12,16,18,20,24,25,29,32,34,36,40,43,45,48,49,52,56,58,61, %T A278517 64,67,70,72,74,77,80,81,84,88,90,93,96,98,100,104,106,109,113,116, %U A278517 120,121,125,128,130,133,136,139,142,144,146,148,152,155,157,160,162,164,168,169,172,176,178,180,184,187,190,193,196,200 %N A278517 a(n) = smallest k for which A260731(k) = n. %H A278517 Antti Karttunen, <a href="/A278517/b278517.txt">Table of n, a(n) for n = 0..11363</a> %F A278517 For all n >= 0, A260731(a(n)) = n. %o A278517 (Scheme, with memoization-macro definec) %o A278517 (definec (A278517 n) (if (zero? n) n (let loop ((k (A278517 (- n 1)))) (if (= (A260731 k) n) k (loop (+ 1 k)))))) %Y A278517 Cf. A260731 (a left inverse), A278518 (first differences), A278519, A278521. %Y A278517 Cf. also A002828, A276573. %K A278517 nonn %O A278517 0,3 %A A278517 _Antti Karttunen_, Nov 28 2016