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A072975
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a(n) = 2^n*binomial(3*n,n)*(3*n+1).
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1
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1, 24, 420, 6720, 102960, 1537536, 22573824, 327444480, 4707014400, 67190323200, 953748956160, 13476348887040, 189694258790400, 2661556369489920, 37240665709608960, 519828326870679552, 7240915141833719808, 100675825501431398400, 1397476339698440601600
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OFFSET
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0,2
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LINKS
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Amiram Eldar, Table of n, a(n) for n = 0..883
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FORMULA
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Sum_{k>=0} 1/a(k) = ( Pi+3*log(2) )/5 = 1.04420683905392583334286...
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MATHEMATICA
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Table[2^n * Binomial[3*n, n] * (3*n + 1), {n, 0, 20}] (* Amiram Eldar, May 04 2022 *)
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PROG
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(PARI) a(n)=2^n*binomial(3*n, n)*(3*n+1)
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CROSSREFS
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Sequence in context: A267166 A016326 A287994 * A062193 A016268 A175199
Adjacent sequences: A072972 A072973 A072974 * A072976 A072977 A072978
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre, Aug 13 2002
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STATUS
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approved
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