A290046 - OEIS

%I #8 Jul 24 2017 11:57:52

%S 1,2,46,899,45181,1981844,183812716,13565497859,1948425055741,

%T 11509621621134,42638364069002866,6290021506693847759,

%U 1672053831207666984241,318158932941670103831384,106827312624343125411048616,25266964023001914822246560759

%N a(n) = |Sum_{k=0..n} (-1)^k*(3k)!!|.

%C a(26) = 2 * 41 * 121157 * 160215276888781 * 1706504288791033 * 4123576055576581869533. Thus a(n) are multiples of 41 for n >= 26.

%t Table[Abs@ Sum[(-1)^k*(3 k)!!, {k, 0, n}], {n, 0, 15}] (* _Michael De Vlieger_, Jul 19 2017 *)

%Y Cf. A006882, A138525.

%K easy,nonn

%O 0,2

%A _XU Pingya_, Jul 19 2017