A004529 Ratios of successive terms are 1,1,1,2,3,3,3,4,5,5,5,6,...

1, 1, 1, 1, 2, 6, 18, 54, 216, 1080, 5400, 27000, 162000, 1134000, 7938000, 55566000, 444528000, 4000752000, 36006768000, 324060912000, 3240609120000, 35646700320000, 392113703520000, 4313250738720000

Offset

0,5

Links

Robert Israel, Table of n, a(n) for n = 0..506

Formula

a(n) = Product_{j=0..n-1} (A180969(2,j+1) + A180969(2,j) + 1) = a(n-1) * (A180969(2,n-1) + A180969(2,n-2) + 1). - Adriano Caroli, Nov 27 2010

a(4*k+j) = 16^k * k! * Gamma(k+1/2)^3*(2*k+1)^j/Gamma(1/2)^3 for 0 <= j <= 3. - Robert Israel, Jun 19 2018

Maple

seq(seq(16^k * k! * GAMMA(k+1/2)^3*(2*k+1)^j/GAMMA(1/2)^3, j=0..3), k=0..10); # Robert Israel, Jun 19 2018

Crossrefs

Sequence in context: A275872 A148455 A094590 * A366550 A238236 A294159

Adjacent sequences: A004526 A004527 A004528 * A004530 A004531 A004532

Keyword

nonn

Author

N. J. A. Sloane

Status

approved