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A226068
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The sum of the positive integers not exceeding 2n that are representable as the sum of two successive sexy primes.
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2
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0, 0, 0, 0, 0, 0, 0, 16, 16, 36, 36, 36, 36, 64, 64, 96, 96, 96, 96, 136, 136, 136, 136, 136, 136, 188, 188, 188, 188, 188, 188, 188, 188, 256, 256, 256, 256, 256, 256, 336, 336, 336, 336, 424, 424, 424, 424, 424
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OFFSET
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1,8
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COMMENTS
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4 divides a(n) for n > 0.
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LINKS
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FORMULA
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a(n) = 2*Sum_{i=1..n} i * (pi(i-3) - pi(i-4)) * (pi(i+3) - pi(i+2)), where pi is the prime counting function (A000720).
a(n) = Sum_{i=1..2*n} c(i), where c is the characteristic function of A104010. - R. J. Mathar, May 28 2013
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MAPLE
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with(numtheory); A226068:=n->sum( 2*i*(pi(i-3) - pi(i-4)) * (pi(i+3) - pi(i+2)) , i = 1..n);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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