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A027766 (n+1)*C(n+1,6). 1
6, 49, 224, 756, 2100, 5082, 11088, 22308, 42042, 75075, 128128, 210392, 334152, 515508, 775200, 1139544, 1641486, 2321781, 3230304, 4427500, 5985980, 7992270, 10548720, 13775580, 17813250, 22824711, 28998144, 36549744, 45726736, 56810600, 70120512, 86017008 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,1

COMMENTS

Number of 8-subsequences of [ 1, n ] with just 1 contiguous pair.

36*a(n) is the number of permutations of (n+1) symbols that 6-commute with an (n+1)-cycle (see A233440 for definition), where 36 = A000757(6). - Luis Manuel Rivera Martínez, Feb 07 2014

LINKS

Table of n, a(n) for n=5..36.

Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).

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

FORMULA

G.f.: (6+x)*x^5/(1-x)^8.

a(n) = C(n+1,6)*C(n+1,1). - Zerinvary Lajos, Jun 08 2005

MAPLE

a:=n->add(binomial(n+1, 6), j=1..n+1): seq(a(n), n=5..33); # Zerinvary Lajos, Feb 12 2007

CROSSREFS

Cf. A233440.

Sequence in context: A173011 A061429 A048357 * A097299 A283226 A292124

Adjacent sequences:  A027763 A027764 A027765 * A027767 A027768 A027769

KEYWORD

nonn,easy

AUTHOR

Thi Ngoc Dinh (via R. K. Guy)

STATUS

approved

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Last modified October 18 14:50 EDT 2019. Contains 328161 sequences. (Running on oeis4.)