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Search: id:A073109
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| A073109 |
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a(n) = prod( p<=n, p) * sum(k=1,n,B(k)*C(2k,k)) where B(k) is the k-th Bernoulli number and p denotes the odd primes. |
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+0
1
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| 0, 0, -7, -35, 295, 2065, -42980, -42980, 1426670, 15693370, -774856236, -10073131068, 692669409432, 692669409432, -63315621131763, -1076365559239971, 126262920264259779, 2398995485020935801, -351338708777824396629, -351338708777824396629
(list; graph; listen)
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OFFSET
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2,3
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COMMENT
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a(n)=a(n+1) for n=2, 8, 14, 20, 24, 26, 32, 34, 38, 44, 48, 50, 54, 56, 62, 64, 68, 74, 76, 80, 84, 86, 90, 92, 94, 98...it seems this si true for n=6k+2, n=10k+24, ...
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PROGRAM
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(PARI) a(n)=(1/2)*prod(i=1, n, i^isprime(i))*sum(k=1, n, bernfrac(k)*binomial(2*k, k))
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CROSSREFS
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Sequence in context: A096686 A165505 A165639 this_sequence A078235 A028389 A041603
Adjacent sequences: A073106 A073107 A073108 this_sequence A073110 A073111 A073112
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KEYWORD
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easy,sign
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 19 2002
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