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 A057054 #7 Feb 10 2020 18:38:35
%S A057054 1,4,7,11,16,21,26,32,38,45,52,59,66,74,82,91,99,108,117,126,136,146,
%T A057054 156,166,177,187,198,210,221,232,244,256,268,280,293,305,318,331,344,
%U A057054 358,371,385,399,413,427,441,456,470,485,500
%N A057054 Let R(i,j) be the rectangle with antidiagonals 1; 2,3; 4,5,6; ...; n^3 is in antidiagonal a(n).
%F A057054 Round(n*(sqrt(2*n))). - _Vladeta Jovovic_, Jun 14 2003
%t A057054 Table[Round[n Sqrt[2n]],{n,50}] (* _Harvey P. Dale_, Feb 10 2020 *)
%Y A057054 Cf. A057045, A057062, A057048, A022846, A057057.
%K A057054 nonn
%O A057054 1,2
%A A057054 _Clark Kimberling_, Jul 30 2000