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A027807 a(n) = 165*(n+1)*C(n+4,11)/4. 1
330, 4455, 32175, 165165, 675675, 2342340, 7147140, 19691100, 49884120, 117781950, 261891630, 552882330, 1115464350, 2162284740, 4045090500, 7330194300, 12907516050, 22145248125, 37105593525, 60841155375, 97796523825, 154345534200, 239501691000, 365847510600 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,1

COMMENTS

Number of 16-subsequences of [ 1, n ] with just 4 contiguous pairs.

LINKS

T. D. Noe, Table of n, a(n) for n = 7..1000

FORMULA

G.f.: 165*(2+x)*x^7/(1-x)^13.

a(n) = C(n+1, 8)*C(n+4, 4). - Zerinvary Lajos, May 26 2005, corrected by R. J. Mathar, Mar 16 2016

MATHEMATICA

Table[165 (n + 1) Binomial[n + 4, 11]/4, {n, 7, 30}] (* or *) Table[Binomial[n + 1, 8] Binomial[n + 4, 4], {n, 7, 30}] (* Michael De Vlieger, Mar 16 2016 *)

CROSSREFS

Sequence in context: A064262 A126997 A205993 * A104476 A140908 A256586

Adjacent sequences:  A027804 A027805 A027806 * A027808 A027809 A027810

KEYWORD

nonn,easy

AUTHOR

thi ngoc dinh (via R. K. Guy)

STATUS

approved

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Last modified July 15 22:48 EDT 2019. Contains 325061 sequences. (Running on oeis4.)