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A136032
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Number of prime factors of composite Mersenne numbers.
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1
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2, 2, 3, 2, 2, 3, 3, 3, 2, 2, 3, 3, 3, 2, 2, 2, 2, 2, 5, 2, 2, 2, 2, 5, 4, 5, 2, 4, 3, 4, 5, 3, 2, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| This sequence is a subset of A088863
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MATHEMATICA
| a = {}; Do[If[PrimeQ[n] && !PrimeQ[2^n - 1], w = 2^n - 1; c = FactorInteger[w]; d = Length[c]; b = 0; Do[b = b + c[[k]][[2]], {k, 1, d}]; AppendTo[a, b]], {n, 2, 150}]; a
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CROSSREFS
| Cf. A003260, A016047, A049479, A088863, A136030, A136031.
Sequence in context: A074595 A084126 A135975 * A140361 A187182 A176208
Adjacent sequences: A136029 A136030 A136031 * A136033 A136034 A136035
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Dec 11 2007
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