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Search: id:A156778
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| 0, 1, 5, 15, 34, 70, 123, 203, 308, 450, 645, 880, 1182, 1547, 1967, 2460, 3048, 3740, 4509, 5396, 6390, 7476, 8701, 10051, 11556, 13250, 15093, 17064, 19194, 21460, 23895, 26660, 29616, 32802, 36159, 39830, 43686, 47804, 52193, 56823, 61740
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OFFSET
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0,3
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COMMENT
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For n>0, the sum of the first n primes, A007504(n), has the opposite parity of n (since both increase by an odd amount, and A007504(n)=2 for n=1.
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FORMULA
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a(n) = A156780( prime(n))/2, where prime(n) = A000040(n) is the n-th prime.
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PROGRAM
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(PARI) vector(80, n, sum(i=1, n, prime(i))*n)/2
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CROSSREFS
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Cf. A156780.
Sequence in context: A084288 A083049 A015627 this_sequence A072186 A051807 A034052
Adjacent sequences: A156775 A156776 A156777 this_sequence A156779 A156780 A156781
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KEYWORD
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nonn
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AUTHOR
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M. F. Hasler (MHasler(AT)univ-ag.fr), Feb 21 2009
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