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 A180498 #13 Sep 01 2012 02:36:07 %S A180498 1,4,4,11,5,16,4,19,1,20,41,19,44,16,45,11,44,4,41,80,36,79,29,76,20, %T A180498 71,9,64,121,55,116,44,109,31,100,16,89,164,76,155,61,144,44,131,25, %U A180498 116,4,99,196,80,181,59,164,36,145,11,124,239,101,220,76,199,49,176,20,151 %N A180498 a(n) = n^2 - 5*floor(n/sqrt(5))^2. %C A180498 a(n)=1 for n=A023039. %H A180498 Zak Seidov, <a href="/A180498/b180498.txt">Table of n, a(n) for n = 1..1000</a> %H A180498 Zak Seidov, <a href="/A180498/a180498.gif">Graphic of A180498</a>. %e A180498 a(4)=11 since 4^2-5*floor(4/sqrt(5))^2=16-5=11. %Y A180498 Cf. A023039, A082532. %K A180498 nonn %O A180498 1,2 %A A180498 _Carmine Suriano_, Sep 08 2010