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A027792 a(n) = 7*(n+1)*C(n+3,7). 0
35, 336, 1764, 6720, 20790, 55440, 132132, 288288, 585585, 1121120, 2042040, 3564288, 5996172, 9767520, 15465240, 23876160, 36038079, 53300016, 77392700, 110510400, 155405250, 215495280, 294987420, 399016800, 533803725 (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 (9,-36,84,-126,126,-84,36,-9,1).

FORMULA

Number of 11-subsequences of [ 1, n ] with just 3 contiguous pairs; g.f. 7*(5+3x)*x^4/(1-x)^9.

a(n) = C(n+1, 5)*C(n+3, 3). - Zerinvary Lajos, May 10 2005, corrected by R. J. Mathar, Feb 10 2016

MATHEMATICA

Table[7(n+1)Binomial[n+3, 7], {n, 4, 30}] (* or *) LinearRecurrence[{9, -36, 84, -126, 126, -84, 36, -9, 1}, {35, 336, 1764, 6720, 20790, 55440, 132132, 288288, 585585}, 30] (* Harvey P. Dale, Jan 04 2015 *)

CROSSREFS

Sequence in context: A220995 A264488 A227058 * A163935 A101099 A027803

Adjacent sequences:  A027789 A027790 A027791 * A027793 A027794 A027795

KEYWORD

nonn

AUTHOR

thi ngoc dinh (via R. K. Guy)

STATUS

approved

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Last modified April 7 15:56 EDT 2020. Contains 333306 sequences. (Running on oeis4.)