A373520 - OEIS

%I #15 Jun 10 2024 10:03:31

%S 1,1,1,1,1,61,361,1261,3361,143641,1829521,12501721,59922721,

%T 2173048021,44315751481,478799701381,3492321094081,116722067432881,

%U 3290135175240481,50242015215929521,508061488330088641,16418736123292904941,585427887134915295241

%N Expansion of e.g.f. exp(x/(1 - x^4)^(1/2)).

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

%F a(n) == 1 mod 60.

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

%Y Cf. A293507, A373519, A373521.

%Y Cf. A373525.

%K nonn

%O 0,6

%A _Seiichi Manyama_, Jun 08 2024