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A027809 143*(n+1)*C(n+4,13)/2. 1
715, 11011, 90090, 520520, 2382380, 9189180, 31039008, 94225560, 261891630, 675745070, 1636014380, 3747960216, 8180071900, 17103786700, 34420042800, 66927861000, 126159017985, 231196390425, 412918656150, 720279159600, 1229442013800, 2056876004040 (list; graph; refs; listen; history; text; internal format)
OFFSET

9,1

LINKS

T. D. Noe, Table of n, a(n) for n = 9..1000

FORMULA

Number of 18-subsequences of [ 1, n ] with just 4 contiguous pairs; g.f. 143*(5+2x)*x^9/(1-x)^15

C(n+10, 10)*C(n+13, 4) - Zerinvary Lajos (zlaja(AT)freemail.hu), May 26 2005

CROSSREFS

Sequence in context: A214186 A029565 A154042 * A222912 A030537 A140919

Adjacent sequences:  A027806 A027807 A027808 * A027810 A027811 A027812

KEYWORD

nonn

AUTHOR

thi ngoc dinh (via R. K. Guy)

STATUS

approved

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Last modified June 19 12:29 EDT 2013. Contains 226404 sequences.