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 A333012 #13 Mar 06 2020 08:10:58 %S A333012 211,215,381,447,602,663,766,807,853,874,1002,1172,1197,1248,1259, %T A333012 1372,1427,1457,1571,1612,1622,1639,1652,1665,1752,1862,1927,1996, %U A333012 2047,2152,2245,2297,2302,2332,2351,2415,2472,2497,2506,2523,2618,2887,2912,2952 %N A333012 Integers which can be written in exactly two ways as a sum of two distinct nonzero pentagonal numbers. %e A333012 211 = P(5) + P(11) = P(1) + P(12) = 35 + 176 = 1 + 210, where P(n) is the n-th pentagonal number A000326. %o A333012 (PARI) is(k) = sum(i=1, sqrt(1+12*k)\6, sqrt(1+24*k+12*i-36*i*i)%6==5) == 2; \\ _Jinyuan Wang_, Mar 06 2020 %Y A333012 Cf. A000326, A333011, A333013, A333014, A333015. %K A333012 nonn %O A333012 1,1 %A A333012 _Olivier Gérard_, Mar 05 2020