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A027768 (n+1)*C(n+1,8). 1
8, 81, 450, 1815, 5940, 16731, 42042, 96525, 205920, 413270, 787644, 1436058, 2519400, 4273290, 7034940, 11277222, 17651304, 27039375, 40619150, 59942025, 87026940, 124472205, 175587750, 244550475, 336585600, 458177148, 617310936, 823753700, 1089372240 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,1

COMMENTS

Number of 10-subsequences of [ 1, n ] with just 1 contiguous pair.

1625*a(n) is the number of permutations of (n+1) symbols that 8-commute with an (n+1)-cycle (see A233440 for definition), where 1625 = A000757(8). - Luis Manuel Rivera Martínez, Feb 07 2014

LINKS

Table of n, a(n) for n=7..35.

Luis Manuel Rivera, Integer sequences and k-commuting permutations, arXiv preprint arXiv:1406.3081, 2014~

FORMULA

G.f.: (8+x)*x^7/(1-x)^10.

MAPLE

a:=n->(sum((numbcomp(n, 9)), j=2..n)):seq(a(n), n=9..33); # Zerinvary Lajos, Aug 26 2008

MATHEMATICA

Table[(n+1)Binomial[n+1, 8], {n, 7, 40}] (* Harvey P. Dale, Jul 08 2017 *)

PROG

(PARI) a(n) = (n+1)*binomial(n+1, 8); \\ Michel Marcus, Jan 31 2014

CROSSREFS

Cf. A233440.

Sequence in context: A247536 A302822 A303515 * A236749 A343274 A240480

Adjacent sequences:  A027765 A027766 A027767 * A027769 A027770 A027771

KEYWORD

nonn,easy

AUTHOR

Thi Ngoc Dinh (via R. K. Guy)

EXTENSIONS

Incorrect formula deleted . - R. J. Mathar, Feb 13 2016

STATUS

approved

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Last modified December 1 11:38 EST 2021. Contains 349429 sequences. (Running on oeis4.)