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A244508
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Number of odd prime powers (A246655) between 2^n and 2^(n+1).
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1
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0, 1, 2, 3, 7, 8, 16, 25, 46, 80, 141, 263, 473, 882, 1628, 3044, 5734, 10779, 20428, 38687, 73653, 140425, 268340, 513866, 986033, 1894409, 3646134, 7027825, 13562625, 26208248, 50698865, 98184467, 190338061, 369326690, 717271793, 1394198586, 2712112561
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OFFSET
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0,3
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LINKS
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FORMULA
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EXAMPLE
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Between 2 and 4, there is just 1 prime power: 3, so a(1) = 1.
Between 4 and 8, there are 2 prime powers: 5 and 7, so a(2) = 2.
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MATHEMATICA
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Table[Count[Range[2^n + 1, 2^(n + 1) - 1], _?PrimePowerQ], {n, 0, 27}] (* Ivan N. Ianakiev, Nov 18 2014 *)
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PROG
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(PARI) a(n) = sum(i=2^n+1, 2^(n+1)-1, isprimepower(i)>0);
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CROSSREFS
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Cf. A246655 (prime powers), A182908 (positions of 2^n among prime powers).
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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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