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 A047831 a(n) = Product_{i=1..n} ((i+5)*(i+6)*(i+7)*(i+8)*(i+9))/(i*(i+1)*(i+2)*(i+3)*(i+4)). 2
 1, 252, 19404, 731808, 16818516, 267227532, 3184461423, 30107635272, 235234907908, 1566039386912, 9095857138368, 46960429261824, 218772384397632, 931020034054176, 3656383418054268, 13365232267026024, 45800747571406905, 148055097314224100 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of tilings of a <5,n,5> hexagon. REFERENCES O. D. Anderson, Find the next sequence, J. Rec. Math., 8 (No. 4, 1975-1976), 241. LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 O. D. Anderson, Find the next sequence, J. Rec. Math., 8 (No. 4, 1975-1976), 241. [Annotated scanned copy] FORMULA a(n) = C(n+5,n+4)*C(n+6,n+3)*C(n+7,n+2)*C(n+8,n+1)*C(n+9,n)/(140*5!). - Zerinvary Lajos, May 29 2007 MAPLE seq(binomial(n+5, n+4)*binomial(n+6, n+3)*binomial(n+7, n+2)*binomial(n+8, n+1)*binomial(n+9, n)/(140*5!), n=0..17); # Zerinvary Lajos, May 29 2007 MATHEMATICA Table[Product[Times@@(i+Range[5, 9])/Times@@(i+Range[0, 4]), {i, n}], {n, 0, 20}] (* Harvey P. Dale, Jan 30 2015 *) PROG (PARI) a(n) = prod(k=1, 5, binomial(n+k+4, n-k+5))/(140*5!); \\ Seiichi Manyama, Apr 02 2021 CROSSREFS Fifth row of array A103905. Sequence in context: A329755 A109924 A281032 * A076013 A180886 A078263 Adjacent sequences:  A047828 A047829 A047830 * A047832 A047833 A047834 KEYWORD nonn,changed AUTHOR EXTENSIONS Definition corrected by Daniel Soll (soll(AT)mathematik.uni-marburg.de), Aug 31 2004 STATUS approved

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Last modified April 13 06:52 EDT 2021. Contains 342935 sequences. (Running on oeis4.)