A082735 - OEIS

A082735

Product of n-th group of terms in A074147.

1, 8, 105, 5760, 328185, 42577920, 5568833025, 1300252262400, 304513870485825, 111644006842368000, 40992233865440682825, 21695920874860629196800, 11492457771692770753505625, 8291067715225260172247040000

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..14.

FORMULA

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

a(n)=A006882[A074148(n)]/A006882[A074148(n-2)]. a(2n-1)=A062031(n). a(2n)=A062030(n). # R. J. Mathar, Jul 17 2007

MAPLE

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

CROSSREFS

Cf. A074147, A074148, A074149, A082736.

Sequence in context: A264014 A222839 A113551 * A024358 A055406 A155632

Adjacent sequences: A082732 A082733 A082734 * A082736 A082737 A082738

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Apr 14 2003

EXTENSIONS

Corrected and extended by R. J. Mathar, Jul 17 2007

STATUS

approved