%I #16 Oct 21 2024 10:55:42
%S 1,-3,-9,81,1215,-40095,-2525985,325852065,83092276575,
%T -42626337882975,-43606743654283425,89350217747626737825,
%U 365889141676531491393375,-2997729737755822508985921375,-49111806293653640164716349886625,1609344780436736134557590069434814625
%N a(n) = product_{i=1..n} ((-2)^i-1).
%C Signed partial products of A062510. This implies that all terms from a(1) on are multiples of 3.
%F A015109(n,k) = a(n)/(a(k)*a(n-k)).
%F a(n) = (-3)^n*A015013(n) for n>0, a(0)=1. [_Bruno Berselli_ and _Alonso del Arte_, Mar 13 2013]
%p A216206 := proc(n)
%p mul( (-2)^i-1, i=1..n) ;
%p end proc:
%t Table[(-1)^n QPochhammer[-2, -2, n], {n, 0, 15}] (* _Bruno Berselli_, Mar 13 2013 *)
%t Table[Product[(-2)^k-1,{k,n}],{n,0,20}] (* _Harvey P. Dale_, Oct 21 2024 *)
%Y Cf. A027871, A005329.
%K sign,easy
%O 0,2
%A _R. J. Mathar_, Mar 12 2013