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A076793
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a(n) = Sum_{k=1..n} 2^prime(k).
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9
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0, 4, 12, 44, 172, 2220, 10412, 141484, 665772, 9054380, 545925292, 2693408940, 140132362412, 2339155617964, 11135248640172, 151872736995500, 9159071991736492, 585619824295159980, 2891462833508853932, 150465415423185266860, 2511648656858007873708
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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a(n) = a(n-1) + 2^prime(n).
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EXAMPLE
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a(1) = 2^prime(1) = 2^2 = 4; a(2) = 4 + 2^prime(2) = 4 + 2^3 = 12.
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MATHEMATICA
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PROG
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(PARI) a(n) = sum(k=1, n, 2^prime(k)) \\ Michel Marcus, Jul 23 2013
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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