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 A307492 #13 Feb 16 2025 08:33:55
%S A307492 1,5,42925,1026745
%N A307492 Numbers that are both centered square and square pyramidal.
%C A307492 If it exists, a(5) > 10^29. - _Bert Dobbelaere_, Apr 12 2019
%H A307492 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CenteredSquareNumber.html">Centered Square Number</a>
%H A307492 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SquarePyramidalNumber.html">Square Pyramidal Number</a>
%t A307492 csQ[n_] := IntegerQ[Sqrt[2*n-1]]; Select[Table[n(n+1)(2n+1)/6, {n, 0, 1000}], csQ] (* _Amiram Eldar_, Apr 11 2019 *)
%Y A307492 Intersection of A000330 and A001844.
%Y A307492 Cf. A008844, A039596, A131750, A307491.
%K A307492 nonn,more
%O A307492 1,2
%A A307492 _Ilya Gutkovskiy_, Apr 10 2019