A109844 a(1) = 1, a(2) = 2, next terms up to a(2n-1) are obtained by multiplying previous terms a(n-1) by n+1, a(n-2) by n+2 etc. a(2) by (2n-2) and a(1) by 2n-1. On similar lines a(2n) = 2n*a(2n-2), a(2n+1) = (2n+1)*a(2n-1) and so on.

1, 2, 3, 8, 5, 48, 21, 16, 9, 160, 231, 576, 65, 112, 45, 32, 17, 576, 855, 2240, 1365, 12672, 5313, 3840, 225, 416, 567, 1344, 145, 240, 93, 64, 33, 2176, 3255, 8640, 5365, 51072, 22113, 16640, 9225, 161280, 228459, 557568, 61425, 103040, 40185, 27648

Offset

1,2

Comments

Might be called a self-dependent or bootstrap sequences. a(n) is a multiple of n by definition. Subsidiary sequences: (i) next n-1 numbers are n times the previous n-1 terms and many more such sequences by variations in coefficients. (ii) a(n) = A109844(n)/n.

Links

Table of n, a(n) for n=1..48.

Example

a(9) = 9.
a(10) = 10*a(8) = 10*16 = 160.
a(11) = 11*21 = 231.

Crossrefs

Sequence in context: A170826 A162537 A369740 * A128779 A112283 A136182

Adjacent sequences: A109841 A109842 A109843 * A109845 A109846 A109847

Keyword

nonn

Author

Amarnath Murthy, Jul 06 2005

Extensions

More terms from Joshua Zucker, May 04 2006

Status

approved