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 A268680 #11 Feb 13 2016 23:17:05 %S A268680 0,1,1,2,3,4,4,5,6,6,6,7,7,7,7,8,9,9,10,11,12,12,13,14,14,14,15,16,16, %T A268680 16,16,17,18,18,19,19,20,21,21,21,22,23,24,24,24,24,24,25,26,26,27,27, %U A268680 28,29,29,29,30,31,31,32,33,33,33,33,34,35,36,36,36,37,38,38,39,39,40,41,41,41,41,41,41,42,43,44 %N A268680 Least monotonic left inverse of A268678. %C A268680 a(n) = number of distinct nonzero values A268395 that occur in range [0 .. n]. %C A268680 Each n occurs A268679(n+1) times. %H A268680 Antti Karttunen, <a href="/A268680/b268680.txt">Table of n, a(n) for n = 0..65537</a> %F A268680 Other identities. For all n >= 0: %F A268680 a(A268678(n)) = n. %o A268680 (Scheme, with _Antti Karttunen_'s IntSeq-library) %o A268680 (define A268680 (LEFTINV-LEASTMONO 0 0 A268678)) %Y A268680 Cf. A268678, A268679, A268395. %Y A268680 Cf. also A268711. %K A268680 nonn %O A268680 0,4 %A A268680 _Antti Karttunen_, Feb 11 2016