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 A238598 #5 Mar 02 2014 03:46:19
%S A238598 1,1,2,2,2,3,3,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,
%T A238598 6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,8,
%U A238598 8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9
%N A238598 Largest integer k such that n >= k^2-k-1 = A165900(k).
%C A238598 Also: Truncation to the integer part of the inverse function of A165900 = x -> x^2-x-1 (strictly increasing for x > 1/2): a(n) = floor(g(n)), where g = A165900^{-1}.
%C A238598 A left inverse of A165900 on the positive integers: a(A165900(n)) = n for all n>0.
%F A238598 a(n) = A000194(n+2) - [n=1], where [P]=1 if P is true, [P]=0 else.
%o A238598 (PARI) A238598(n)=ceil(sqrtint(4*n+8)/2)-(n==1)
%K A238598 nonn
%O A238598 0,3
%A A238598 _M. F. Hasler_, Mar 01 2014