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 A097045 #2 Mar 30 2012 17:36:43 %S A097045 1,0,-1,-1,-1,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18, %T A097045 19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41, %U A097045 42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,71,71,71,71,71,71,71,71 %N A097045 a(n) = a(n-1) - a(floor(sqrt(n))) for n > 1; a(1) = 1. %F A097045 a(1)=1; a(n) = a(n-1) - a(floor(sqrt(n))) for n > 1. %Y A097045 Cf. A097046 ( a(n-1) + a(floor(sqrt(n))) ). %K A097045 sign %O A097045 1,11 %A A097045 _Rick L. Shepherd_, Jul 20 2004