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 A374288 #11 Jul 03 2024 08:34:34 %S A374288 2,0,9,81,189,441,1449,10206,3969,12789,13041,35721,30429,194481, %T A374288 117369,115101,186921,2893401,273861 %N A374288 a(n) is the smallest nonnegative integer k where there are exactly n nonnegative integer solutions to x^2 + 5*y^2 = k. %C A374288 For n > 1, a(n) is the smallest nonnegative k such that A216283(k) = n. %C A374288 a(20) = 378189. %C A374288 a(21) = 1035909. %C A374288 a(22) = 9506889. %C A374288 a(23) = 2099601. %C A374288 a(24) = 882441. %C A374288 a(25) = 5639949. %C A374288 a(26) = 85562001. %C A374288 a(27) = 6765381. %C A374288 a(28) = 3403701. %C A374288 a(30) = 3925341. %C A374288 a(32) = 5420709. %C A374288 a(33) = 83908629. %C A374288 a(35) = 50759541. %C A374288 a(36) = 7941969. %C A374288 a(38) = 102880449. %C A374288 a(40) = 15505749. %C A374288 a(41) = 170067681. %C A374288 a(42) = 35328069. %o A374288 (PARI) b(n, k) = sum(i=0, sqrtint(n), sum(j=0, sqrtint(n\k), i^2+k*j^2==n)); %o A374288 a(n, k=5) = my(cnt=0); while(b(cnt, k)!=n, cnt++); cnt; %Y A374288 Cf. A374285, A374286. %Y A374288 Cf. A216283. %K A374288 nonn,more %O A374288 0,1 %A A374288 _Seiichi Manyama_, Jul 02 2024