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 A255120 #7 Feb 14 2015 21:29:28 %S A255120 0,0,0,1,0,1,2,0,1,2,3,4,0,1,2,3,4,5,6,7,8,0,1,2,3,4,5,6,7,8,9,10,11, %T A255120 12,13,14,15,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21, %U A255120 22,23,24,25,26,27,28,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19 %N A255120 After the first zero, numbers from 0 to A255071(n)-1 followed by numbers from 0 to A255071(n+1)-1, etc. %C A255120 An auxiliary sequence for computing A255122 and A255056. %H A255120 Antti Karttunen, <a href="/A255120/b255120.txt">Table of n, a(n) for n = 0..721</a> %F A255120 a(0) = 0; and for n >= 1, a(n) = n - A255062(A255121(n)). %o A255120 (Scheme) (define (A255120 n) (if (zero? n) n (- n (A255062 (A255121 n))))) %Y A255120 Cf. A255056, A255062, A255121, A255122. %Y A255120 Similar sequence: A218601. %K A255120 nonn %O A255120 0,7 %A A255120 _Antti Karttunen_, Feb 14 2015