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 A321208 #9 Oct 30 2018 08:59:47
%S A321208 1,1,0,2,7,31,167,1046,7949,60487,490753,4232323,39877499,401064825,
%T A321208 4191449438,45993709856,526379057073,6284584514360,77594053714675,
%U A321208 990497759689341,13053609492660678,177385290308586391,2480368806876623852,35617209442716039028,524705024124493308382
%N A321208 a(n) = [x^(n*(n+1)*(2*n+1)/6)] Product_{k=1..n} Sum_{m>=0} x^(k*m^2).
%C A321208 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*n+1)/6.
%F A321208 a(n) = [x^(n*(n+1)*(2*n+1)/6)] Product_{k=1..n} (theta_3(x^k) + 1)/2, where theta_3() is the Jacobi theta function.
%e A321208 1*0^2 + 2*1^2 + 3*2^2 + 4*3^2 + 5*1^2 = 55.
%e A321208 1*0^2 + 2*1^2 + 3*4^2 + 4*0^2 + 5*1^2 = 55.
%e A321208 1*0^2 + 2*2^2 + 3*3^2 + 4*0^2 + 5*2^2 = 55.
%e A321208 1*0^2 + 2*4^2 + 3*1^2 + 4*0^2 + 5*2^2 = 55.
%e A321208 1*0^2 + 2*5^2 + 3*0^2 + 4*0^2 + 5*1^2 = 55.
%e A321208 1*1^2 + 2*1^2 + 3*1^2 + 4*1^2 + 5*3^2 = 55.
%e A321208 1*1^2 + 2*1^2 + 3*4^2 + 4*1^2 + 5*0^2 = 55.
%e A321208 1*1^2 + 2*3^2 + 3*0^2 + 4*2^2 + 5*2^2 = 55.
%e A321208 1*1^2 + 2*3^2 + 3*0^2 + 4*3^2 + 5*0^2 = 55.
%e A321208 1*1^2 + 2*3^2 + 3*2^2 + 4*1^2 + 5*2^2 = 55.
%e A321208 1*1^2 + 2*3^2 + 3*3^2 + 4*1^2 + 5*1^2 = 55.
%e A321208 1*1^2 + 2*5^2 + 3*0^2 + 4*1^2 + 5*0^2 = 55.
%e A321208 1*2^2 + 2*0^2 + 3*3^2 + 4*1^2 + 5*2^2 = 55.
%e A321208 1*2^2 + 2*1^2 + 3*0^2 + 4*1^2 + 5*3^2 = 55.
%e A321208 1*2^2 + 2*2^2 + 3*3^2 + 4*2^2 + 5*0^2 = 55.
%e A321208 1*2^2 + 2*3^2 + 3*2^2 + 4*2^2 + 5*1^2 = 55.
%e A321208 1*2^2 + 2*4^2 + 3*1^2 + 4*2^2 + 5*0^2 = 55.
%e A321208 1*3^2 + 2*1^2 + 3*1^2 + 4*3^2 + 5*1^2 = 55.
%e A321208 1*3^2 + 2*3^2 + 3*2^2 + 4*2^2 + 5*0^2 = 55.
%e A321208 1*4^2 + 2*0^2 + 3*1^2 + 4*2^2 + 5*2^2 = 55.
%e A321208 1*4^2 + 2*0^2 + 3*1^2 + 4*3^2 + 5*0^2 = 55.
%e A321208 1*4^2 + 2*2^2 + 3*3^2 + 4*1^2 + 5*0^2 = 55.
%e A321208 1*4^2 + 2*3^2 + 3*0^2 + 4*2^2 + 5*1^2 = 55.
%e A321208 1*4^2 + 2*3^2 + 3*2^2 + 4*1^2 + 5*1^2 = 55.
%e A321208 1*4^2 + 2*4^2 + 3*1^2 + 4*1^2 + 5*0^2 = 55.
%e A321208 1*5^2 + 2*1^2 + 3*2^2 + 4*2^2 + 5*0^2 = 55.
%e A321208 1*5^2 + 2*3^2 + 3*1^2 + 4*1^2 + 5*1^2 = 55.
%e A321208 1*5^2 + 2*3^2 + 3*2^2 + 4*0^2 + 5*0^2 = 55.
%e A321208 1*6^2 + 2*0^2 + 3*1^2 + 4*2^2 + 5*0^2 = 55.
%e A321208 1*6^2 + 2*1^2 + 3*2^2 + 4*0^2 + 5*1^2 = 55.
%e A321208 1*7^2 + 2*1^2 + 3*0^2 + 4*1^2 + 5*0^2 = 55.
%e A321208 So a(5) = 31.
%Y A321208 Cf. A000122, A320932, A321181, A321186.
%K A321208 nonn
%O A321208 0,4
%A A321208 _Seiichi Manyama_, Oct 30 2018