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A010973
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a(n) = binomial(n,20).
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3
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1, 21, 231, 1771, 10626, 53130, 230230, 888030, 3108105, 10015005, 30045015, 84672315, 225792840, 573166440, 1391975640, 3247943160, 7307872110, 15905368710, 33578000610, 68923264410, 137846528820, 269128937220, 513791607420, 960566918220, 1761039350070
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OFFSET
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20,2
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COMMENTS
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (21, -210, 1330, -5985, 20349, -54264, 116280, -203490, 293930, -352716, 352716, -293930, 203490, -116280, 54264, -20349, 5985, -1330, 210, -21, 1).
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FORMULA
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a(n+19) = n*(n+1)*(n+2)*(n+3)*(n+4)*(n+5)*(n+6)*(n+7)*(n+8)*(n+9)*(n+10)*(n+11)*(n+12)*(n+13)*(n+14)*(n+15)*(n+16)*(n+17)*(n+18)*(n+19)/20!. - Artur Jasinski, Dec 02 2007; R. J. Mathar, Jul 07 2009
Sum_{n>=20} 1/a(n) = 20/19.
Sum_{n>=20} (-1)^n/a(n) = A001787(20)*log(2) - A242091(20)/19! = 10485760*log(2) - 21149710469086/2909907 = 0.9562240549... (End)
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MAPLE
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MATHEMATICA
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PROG
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(PARI) for(n=20, 50, print1(binomial(n, 20), ", ")) \\ G. C. Greubel, Nov 23 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Some formulas adjusted to the offset by R. J. Mathar, Jul 07 2009
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STATUS
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approved
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