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 A136359 #16 Jun 07 2021 01:15:39
%S A136359 36,81,144,289,484,576,625,676,3600,7396,9801,14400,35344,40000,40804,
%T A136359 44100,45796,56644,59049,71824,112896,121104,172225,226576,231361,
%U A136359 254016,274576,290521,319225,362404,480249,495616,518400,527076,535824
%N A136359 Perfect squares in A133459; or perfect squares that are the sums of two nonzero pentagonal pyramidal numbers.
%C A136359 Corresponding numbers m such that m^2 = a(n) are listed in A136360.
%C A136359 Note that some numbers in A136360 are also perfect squares. The corresponding numbers k such that m = k^2 are listed in A136361.
%C A136359 Includes all nonzero members of A099764: this occurs when the two pentagonal pyramidal numbers are both equal to i^2*(i+1)/2 where i+1 is a square. - _Robert Israel_, Feb 04 2020
%H A136359 Robert Israel, <a href="/A136359/b136359.txt">Table of n, a(n) for n = 1..985</a>
%F A136359 a(n) = A136360(n)^2.
%e A136359 A133459 begins {2, 7, 12, 19, 24, 36, 41, 46, 58, 76, 80, 81, 93, 115, 127, 132, 144, 150, 166, 197, 201, 202, 214, 236, 252, 271, 289, ...}.
%e A136359 Thus a(1) = 36, a(2) = 81, a(3) = 144, a(4) = 289 that are the perfect squares in A133459.
%p A136359 N:= 200: # for terms up to N^2*(N+1)/2.
%p A136359 PP:= [seq(i^2*(i+1)/2, i=1..N)]:
%p A136359 PP2:= sort(convert(select(`<=`,{seq(seq(PP[i]+PP[j],j=i..N),i=1..N)},PP[-1]),list)):
%p A136359 select(issqr,PP2); # _Robert Israel_, Feb 04 2020
%t A136359 Select[ Intersection[ Flatten[ Table[ i^2*(i+1)/2 + j^2*(j+1)/2, {i,1,300}, {j,1,i} ] ] ], IntegerQ[ Sqrt[ # ] ] & ]
%Y A136359 Cf. A136360, A136361, A133459, A002311, A002411, A053721, A099764.
%K A136359 nonn
%O A136359 1,1
%A A136359 _Alexander Adamchuk_, Dec 25 2007