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 A132304 #9 Aug 31 2025 10:45:49
%S A132304 1,3,115,5157,281907,16688953,1043460469,67769148555,4527813298227,
%T A132304 309207348577017,21487099512128265,1514508365575327455,
%U A132304 108015601963868232885,7780760215720406500095,565264860408377433558523,41369186303433709127364757,3047140179357736909766753331
%N A132304 Sum of fourth powers of trinomial coefficients: a(n) = Sum_{k=0..2n} trinomial(n,k)^4 where trinomial(n,k) = [x^k] (1 + x + x^2)^n.
%C A132304 Conjecture: the supercongruence a(n*p^k) == a(n*p^(k-1)) (mod p^(2*k)) holds for all primes p >= 5 and positive integers n and k. - _Peter Bala_, Aug 29 2025
%o A132304 (PARI) a(n)=sum(k=0,2*n,polcoeff((1+x+x^2)^n,k)^4)
%Y A132304 Cf. A027907, A082758, A132303, A132305.
%K A132304 nonn,changed
%O A132304 0,2
%A A132304 _Paul D. Hanna_, Aug 18 2007