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Search: id:A109580
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| 3, 3, 7, 7, 11, 11, 11, 11, 13, 13, 17, 17, 17, 17, 23, 23, 29, 29, 29, 29, 61, 61, 71, 71, 71, 71, 83, 83, 83, 83, 83, 83, 107, 107, 107, 107, 137, 137, 137, 137, 137, 137, 137, 137, 149, 149, 193, 193, 227, 227, 227, 227, 227, 227, 241, 241, 241, 241, 281, 281, 307
(list; graph; listen)
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OFFSET
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1,1
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MAPLE
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with(numtheory): a:=proc(n) if isprime(sum((pi(k+1)-pi(k))*(ithprime(k+1)-ithprime(k)), k=1..n))=true then sum((pi(k+1)-pi(k))*(ithprime(k+1)-ithprime(k)), k=1..n) else fi end: seq(a(n), n=1..230);
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MATHEMATICA
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an = Table[(PrimePi[n + 1] - PrimePi[n])*(Prime[n + 1] - Prime[n]), {n, 1, 400}] a[0] = 0; a[n_] := a[n] = a[n - 1] + an[[n]] aa = Flatten[Table[If[PrimeQ[a[n]] == True, a[n], {}], {n, 0, Length[an]}]]
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CROSSREFS
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Cf. A001223, A010051.
Sequence in context: A063212 A088147 A109579 this_sequence A128508 A083743 A126990
Adjacent sequences: A109577 A109578 A109579 this_sequence A109581 A109582 A109583
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KEYWORD
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nonn
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Jun 29 2005
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