A385607 - OEIS

%I #8 Jul 04 2025 10:04:47

%S 1,1,121,721,115921,1254121,175667521,2723150641,328524651841,

%T 6553910658241,694593264839761,16751100559753561,1592929589394223081,

%U 44555491032952142881,3872288533662063462481,121957120480085202781681,9836937778718128127534881,341177468192261294809070401

%N Diagonal of the rational function 1/(1 - (v^2 + w^2 + x^2 + y^2 + z^2 + v*w*x*y*z)).

%F a(n) = Sum_{k=0..floor(n/2)} (n+3*k)!/(k!^5 * (n-2*k)!).

%o (PARI) a(n) = sum(k=0, n\2, (n+3*k)!/(k!^5*(n-2*k)!));

%Y Cf. A082489, A361636, A361703, A385606.

%K nonn

%O 0,3

%A _Seiichi Manyama_, Jul 04 2025