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 A028658 #16 Jul 08 2025 18:44:36 %S A028658 1,4,4,0,4,8,8,16,12,20,24,0,40,24,32,16,36,24,44,16,40,16,32,4,80,28, %T A028658 48,48,48,24,80,48,84,80,56,64,92,40,64,48,88,40,96,48,112,88,4,48, %U A028658 120,68,92,80,96,56,136,64,112,96,96,80,192,56,120,128,140,96 %N A028658 Expansion of (theta_3(z)*theta_3(23z) + theta_2(z)*theta_2(23z))^2. %D A028658 Köklüce, Bülent. "Cusp forms in S_6 (Gamma_ 0(23)), S_8 (Gamma_0 (23)) and the number of representations of numbers by some quadratic forms in 12 and 16 variables." The Ramanujan Journal 34.2 (2014): 187-208. See F_2, p. 195. %H A028658 Jinyuan Wang, <a href="/A028658/b028658.txt">Table of n, a(n) for n = 0..1000</a> %o A028658 (PARI) a(n) = if( n<0, 0, polcoeff( (1 + 2 * x * Ser(qfrep( [ 2, 1; 1, 12], n, 1)))^2, n)); \\ _Jinyuan Wang_, Feb 19 2020 %K A028658 nonn %O A028658 0,2 %A A028658 _N. J. A. Sloane_ %E A028658 More terms from _Jinyuan Wang_, Feb 19 2020