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 A353064 #34 Jul 12 2022 21:08:22
%S A353064 0,1,196,99225
%N A353064 Numbers simultaneously square and heptagonal pyramidal.
%C A353064 Is this sequence finite?
%C A353064 No other terms < 10^32. - _Michael S. Branicky_, Jul 12 2022
%H A353064 ProofWiki, <a href="https://proofwiki.org/wiki/Heptagonal_Pyramidal_Numbers_which_are_Square">Heptagonal Pyramidal Numbers which are Square</a>
%e A353064 196 is a term because 196 = 14^2 is a perfect square and 196 = 6*(6+1)*(5*6-2)/6 is the 6th heptagonal pyramidal number.
%p A353064 select(issqr, [seq(n*(n+1)*(5*n-2)/6, n=0..50)])[]; # _Alois P. Heinz_, Apr 21 2022
%t A353064 Select[Table[n*(n + 1)*(5*n - 2)/6, {n, 0, 100}], IntegerQ @ Sqrt[#] &] (* _Amiram Eldar_, Apr 21 2022 *)
%Y A353064 Intersection of A000290 and A002413.
%Y A353064 Cf. A003556 (tetrahedral and square), 1 and 4900 are only squares that are square pyramidal, A277792 (pentagonal pyramidal and square).
%K A353064 nonn,more
%O A353064 1,3
%A A353064 _Kelvin Voskuijl_, Apr 21 2022