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 A057049 #8 May 28 2015 09:45:43 %S A057049 1,1,3,1,4,8,4,9,3,9,1,8,16,6,15,3,13,24,10,22,6,19,1,15,30,10,26,4, %T A057049 21,39,15,34,8,28,49,21,43,13,36,4,28,53,19,45,9,36,64,26,55,15,45,3, %U A057049 34,66,22,55,9,43,78,30,66,16,53,1,39,78,24,64 %N A057049 Let R(i,j) be the rectangle with antidiagonals 1; 2,3; 4,5,6; ...; each k is an R(i(k),j(k)) and A057049(n) = i(n^2). %H A057049 Ivan Neretin, <a href="/A057049/b057049.txt">Table of n, a(n) for n = 1..10000</a> %t A057049 # - (l = Floor[Sqrt[2 #] - 1/2]) (l + 1)/2 & /@ ((Range@68)^2) (* _Ivan Neretin_, May 28 2015 *) %Y A057049 Cf. A002260 = i(n), A057052 = i(n^3). %K A057049 nonn %O A057049 1,3 %A A057049 _Clark Kimberling_, Jul 30 2000