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A126613
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a(1)=1. a(n) = a(n-1) + (number of terms, from among terms a(1) through a(n-1), which are powers of primes {including 1}).
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0
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1, 2, 4, 7, 11, 16, 22, 28, 34, 40, 46, 52, 58, 64, 71, 79, 88, 97, 107, 118, 129, 140, 151, 163, 176, 189, 202, 215, 228, 241, 255, 269, 284, 299, 314, 329, 344, 359, 375, 391, 407, 423, 439, 456, 473, 490, 507, 524, 541, 559, 577, 596, 615, 634, 653, 673, 694
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OFFSET
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1,2
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LINKS
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EXAMPLE
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There are 7 prime powers (1,2,4,7,11,16,64) among the first 14 terms of the sequence. So a(15) = a(14) + 7 = 71.
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MATHEMATICA
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a = {1}; Do[AppendTo[a, a[[ -1]] + 1 + Length[Select[a, Length[FactorInteger[ # ]] == 1 &]]], {60}]; a (* Stefan Steinerberger, Oct 16 2007 *)
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CROSSREFS
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KEYWORD
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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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