A373521 - OEIS

%I #16 Jun 10 2024 10:03:37

%S 1,1,1,1,1,91,541,1891,5041,249481,3424681,24365881,119821681,

%T 4208219731,96849813061,1133147785771,8728726799521,251218306095121,

%U 8116398738418321,138787857114672241,1523943014238675361,39648007379230971211,1599866285860593980461

%N Expansion of e.g.f. exp(x/(1 - x^4)^(3/4)).

%F a(n) = n! * Sum_{k=0..floor(n/4)} binomial(3*n/4-2*k-1,k)/(n-4*k)!.

%F a(n) == 1 mod 90.

%o (PARI) a(n) = n!*sum(k=0, n\4, binomial(3*n/4-2*k-1, k)/(n-4*k)!);

%Y Cf. A293507, A373519, A373520.

%Y Cf. A373526.

%K nonn

%O 0,6

%A _Seiichi Manyama_, Jun 08 2024