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A027779 a(n) = 3*(n+1)*C(n+2,6). 0
15, 126, 588, 2016, 5670, 13860, 30492, 61776, 117117, 210210, 360360, 594048, 946764, 1465128, 2209320, 3255840, 4700619, 6662502, 9287124, 12751200, 17267250, 23088780, 30515940, 39901680, 51658425 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Table of n, a(n) for n=4..28.

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

FORMULA

Number of 9-subsequences of [ 1, n ] with just 2 contiguous pairs; g.f. 3*(5+2x)*x^4/(1-x)^8.

a(n) = C(n+1, 5)*C(n+2, 2). - Zerinvary Lajos, May 13 2005, corrected by R. J. Mathar, Feb 10 2016

MAPLE

[seq (stirling2(n+1, n)*binomial(n, 5), n=5..29)]; # Zerinvary Lajos, Dec 06 2006

CROSSREFS

Sequence in context: A071080 A193365 A069975 * A073509 A198850 A283120

Adjacent sequences:  A027776 A027777 A027778 * A027780 A027781 A027782

KEYWORD

nonn,easy

AUTHOR

thi ngoc dinh (via R. K. Guy)

STATUS

approved

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Last modified February 20 13:40 EST 2020. Contains 332077 sequences. (Running on oeis4.)