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 A321181 #19 Oct 29 2018 12:09:42
%S A321181 1,1,2,7,28,262,3428,52289,1147221,30161625,893291633,30894822277,
%T A321181 1214415301634,52617692115135,2528123847871538,133088227043557512,
%U A321181 7574733515354756765,466116310963215784930,30810712157925101729430,2173319693639115252360852,163247410881483617710298406
%N A321181 a(n) = [x^((n*(n+1)/2)^2)] Product_{k=1..n} Sum_{m>=0} x^(k*m^2).
%C A321181 Also the number of nonnegative integer solutions (a_1, a_2, ... , a_n) to the equation a_1^2 + 2*a_2^2 + ... + n*a_n^2 = (n*(n+1)/2)^2.
%e A321181 1* 0^2 + 2*0^2 + 3*0^2 + 4*5^2 = 100.
%e A321181 1* 0^2 + 2*6^2 + 3*2^2 + 4*2^2 = 100.
%e A321181 1* 1^2 + 2*2^2 + 3*3^2 + 4*4^2 = 100.
%e A321181 1* 1^2 + 2*2^2 + 3*5^2 + 4*2^2 = 100.
%e A321181 1* 1^2 + 2*4^2 + 3*1^2 + 4*4^2 = 100.
%e A321181 1* 1^2 + 2*6^2 + 3*3^2 + 4*0^2 = 100.
%e A321181 1* 2^2 + 2*4^2 + 3*0^2 + 4*4^2 = 100.
%e A321181 1* 2^2 + 2*4^2 + 3*4^2 + 4*2^2 = 100.
%e A321181 1* 3^2 + 2*0^2 + 3*3^2 + 4*4^2 = 100.
%e A321181 1* 3^2 + 2*0^2 + 3*5^2 + 4*2^2 = 100.
%e A321181 1* 3^2 + 2*6^2 + 3*1^2 + 4*2^2 = 100.
%e A321181 1* 4^2 + 2*0^2 + 3*4^2 + 4*3^2 = 100.
%e A321181 1* 4^2 + 2*2^2 + 3*2^2 + 4*4^2 = 100.
%e A321181 1* 4^2 + 2*4^2 + 3*4^2 + 4*1^2 = 100.
%e A321181 1* 4^2 + 2*6^2 + 3*2^2 + 4*0^2 = 100.
%e A321181 1* 5^2 + 2*0^2 + 3*5^2 + 4*0^2 = 100.
%e A321181 1* 5^2 + 2*2^2 + 3*1^2 + 4*4^2 = 100.
%e A321181 1* 5^2 + 2*4^2 + 3*3^2 + 4*2^2 = 100.
%e A321181 1* 5^2 + 2*6^2 + 3*1^2 + 4*0^2 = 100.
%e A321181 1* 6^2 + 2*0^2 + 3*0^2 + 4*4^2 = 100.
%e A321181 1* 6^2 + 2*0^2 + 3*4^2 + 4*2^2 = 100.
%e A321181 1* 7^2 + 2*2^2 + 3*3^2 + 4*2^2 = 100.
%e A321181 1* 7^2 + 2*4^2 + 3*1^2 + 4*2^2 = 100.
%e A321181 1* 8^2 + 2*0^2 + 3*0^2 + 4*3^2 = 100.
%e A321181 1* 8^2 + 2*2^2 + 3*2^2 + 4*2^2 = 100.
%e A321181 1* 8^2 + 2*4^2 + 3*0^2 + 4*1^2 = 100.
%e A321181 1* 9^2 + 2*0^2 + 3*1^2 + 4*2^2 = 100.
%e A321181 1*10^2 + 2*0^2 + 3*0^2 + 4*0^2 = 100.
%e A321181 So a(4) = 28.
%Y A321181 Cf. A000122, A000537, A300446, A320932.
%K A321181 nonn
%O A321181 0,3
%A A321181 _Seiichi Manyama_, Oct 29 2018
%E A321181 a(17)-a(20) from _Alois P. Heinz_, Oct 29 2018