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A076700
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Number of prime powers of prime numbers less than 10^n.
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0
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3, 7, 18, 40, 88, 208, 513, 1345, 3605, 9965, 27984, 79815, 230184, 669541, 1961782, 5781027, 17121898, 50926700, 152037454, 455379086, 1367866472, 4119420084, 12434683582, 37613680284, 113995431428, 346090115288, 1052421037283, 3205047207003, 9774084239631
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(2) = 7 because 4, 8, 9, 25, 27, 32 and 49 are the only prime powers of prime numbers less than 100.
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MATHEMATICA
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pp = Sort[ Flatten[ Table[ Prime[n]^Prime[i], {n, 1, PrimePi[ Sqrt[10^17]]}, {i, 1, PrimePi[ Floor[ Log[ Prime[n], 10^17]]]}]]]; a = {}; k = 1; Do[ While[ pp[[k]] <= 10^n, k++ ]; a = Append[a, k-1], {n, 1, 17}]
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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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