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 A027783 a(n) = 5*(n+1)*binomial(n+2,10). 1
 45, 550, 3630, 17160, 65065, 210210, 600600, 1555840, 3719430, 8314020, 17551820, 35271600, 67897830, 125847260, 225544440, 392251200, 663966875, 1096717050, 1771619850, 2804201400, 4356527175, 6652824750, 9999397200, 14809766400, 21636143100, 31208497320 (list; graph; refs; listen; history; text; internal format)
 OFFSET 8,1 LINKS T. D. Noe, Table of n, a(n) for n = 8..1000 FORMULA Number of 13-subsequences of [ 1, n ] with just 2 contiguous pairs; g.f. 5*(9+2x)*x^8/(1-x)^12. a(n) = C(n+1, 9)*C(n+2, 2). - Zerinvary Lajos, May 13 2005, corrected R. J. Mathar, Mar 15 2016 MATHEMATICA Table[5(n+1)Binomial[n+2, 10], {n, 8, 30}] (* Harvey P. Dale, Jan 21 2012 *) CROSSREFS Sequence in context: A283116 A223047 A147842 * A160837 A160838 A189350 Adjacent sequences:  A027780 A027781 A027782 * A027784 A027785 A027786 KEYWORD nonn,easy AUTHOR thi ngoc dinh (via R. K. Guy) STATUS approved

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Last modified May 6 16:03 EDT 2021. Contains 343586 sequences. (Running on oeis4.)