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Search: id:A071259
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| A071259 |
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Integer part of the arithmetic mean of the n-th prime p(n) and the n-th composite number C(n). |
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+0
3
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| 3, 4, 6, 8, 10, 12, 15, 17, 19, 23, 25, 29, 31, 33, 36, 39, 43, 44, 48, 51, 53, 56, 59, 62, 67, 70, 71, 74, 76, 79, 86, 89, 93, 94, 100, 101, 105, 109, 111, 115, 118, 120, 126, 128, 130, 132, 138, 145, 148, 149, 152, 156, 158, 163, 167, 170, 174, 176, 179, 182, 184
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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Floor [ (p(n) + C(n))/2]
a(n)=Floor[[A000040(n)+A002808(n)]/2]; Prime[n]>a(n)>Composite[n]
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EXAMPLE
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a(7) = {p(7) + C(7)}/2 = (17 + 14)/2 = 15.
p(9) = 23, C(9) = 16, average = 19.5, a(9) = 19.
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MATHEMATICA
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c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Do[s=(Prime[n]+c[n])/2; If[IntegerQ[s], Print[s]], {n, 1, 256}]
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CROSSREFS
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Cf. A000040, A002808, A073432, A073433, A071260.
Adjacent sequences: A071256 A071257 A071258 this_sequence A071260 A071261 A071262
Sequence in context: A092535 A135667 A025201 this_sequence A054041 A092137 A059608
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 30 2002
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EXTENSIONS
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More terms from Labos E. (labos(AT)ana.sote.hu), Jul 31 2002
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