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A027765 a(n) = (n+1)*binomial(n+1,5). 2
5, 36, 147, 448, 1134, 2520, 5082, 9504, 16731, 28028, 45045, 69888, 105196, 154224, 220932, 310080, 427329, 579348, 773927, 1020096, 1328250, 1710280, 2179710, 2751840, 3443895, 4275180, 5267241, 6444032, 7832088, 9460704, 11362120, 13571712, 16128189 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

COMMENTS

8*a(n) is the number of permutations of (n+1) symbols that 5-commute with an (n+1)-cycle (see A233440 for definition), where 8 = A000757(5). - Luis Manuel Rivera Martínez, Feb 07 2014

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 4..1000

Luis Manuel Rivera, Integer sequences and k-commuting permutations, arXiv preprint arXiv:1406.3081 [math.CO], 2014.

Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).

FORMULA

Number of 7-subsequences of [ 1, n ] with just 1 contiguous pair.

G.f.: (5+x)*x^4/(1-x)^7.

MAPLE

a:=n->(sum((numbcomp(n, 6)), j=2..n)):seq(a(n), n=6..34); # Zerinvary Lajos, Aug 26 2008

MATHEMATICA

Table[(n+1)Binomial[n+1, 5], {n, 4, 40}] (* or *) LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {5, 36, 147, 448, 1134, 2520, 5082}, 40] (* Harvey P. Dale, Jan 15 2017 *)

PROG

(MAGMA) [(n+1)*Binomial(n+1, 5): n in [4..40]]; // Vincenzo Librandi, Aug 09 2017

CROSSREFS

Sequence in context: A217166 A275143 A276249 * A196481 A096945 A063417

Adjacent sequences:  A027762 A027763 A027764 * A027766 A027767 A027768

KEYWORD

nonn,easy

AUTHOR

Thi Ngoc Dinh (via R. K. Guy)

EXTENSIONS

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

STATUS

approved

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Last modified October 28 13:26 EDT 2021. Contains 348329 sequences. (Running on oeis4.)