

A244508


Number of odd prime powers (A246655) between 2^n and 2^(n+1).


1



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

0,3


LINKS



FORMULA



EXAMPLE

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.


MATHEMATICA

Table[Count[Range[2^n + 1, 2^(n + 1)  1], _?PrimePowerQ], {n, 0, 27}] (* Ivan N. Ianakiev, Nov 18 2014 *)


PROG

(PARI) a(n) = sum(i=2^n+1, 2^(n+1)1, isprimepower(i)>0);


CROSSREFS

Cf. A246655 (prime powers), A182908 (positions of 2^n among prime powers).


KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



