login
Product of n-th group of terms in A074147.
2

%I #7 Aug 07 2015 03:06:30

%S 1,8,105,5760,328185,42577920,5568833025,1300252262400,

%T 304513870485825,111644006842368000,40992233865440682825,

%U 21695920874860629196800,11492457771692770753505625,8291067715225260172247040000

%N Product of n-th group of terms in A074147.

%F a(1) = 1, a(2n) = product of next 2n even numbers. a(2n+1) = product of next 2n+1 odd numbers.

%F a(n)=A006882[A074148(n)]/A006882[A074148(n-2)]. a(2n-1)=A062031(n). a(2n)=A062030(n). # _R. J. Mathar_, Jul 17 2007

%p A074148 := proc(n) (2*n^2+4*n+(-1)^n-1)/4 ; end: A082735 := proc(n) doublefactorial(A074148(n))/doublefactorial(A074148(n-2)) ; end: seq(A082735(n),n=1..20) ; # _R. J. Mathar_, Jul 17 2007

%Y Cf. A074147, A074148, A074149, A082736.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Apr 14 2003

%E Corrected and extended by _R. J. Mathar_, Jul 17 2007