A327247 Number of odd prime powers <= n (with exponents > 0).

0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 16, 16, 16, 16, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 20, 20, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 24, 24, 24

Offset

1,5

Links

Table of n, a(n) for n=1..75.

Formula

a(n) = A025528(n) - A000523(n).

Mathematica

Table[Sum[Boole[OddQ[k] && PrimePowerQ[k]], {k, 1, n}], {n, 1, 75}]

Prog

(PARI) a(n) = {sum(k=2, primepi(n), logint(n, prime(k)))} \\ Andrew Howroyd, Sep 14 2019

Crossrefs

Cf. A000523, A025528, A033270, A061345, A065515, A069637, A085501, A174275 (first differences), A246655, A285879.

Sequence in context: A375114 A096029 A206915 * A210609 A210608 A362131

Adjacent sequences: A327244 A327245 A327246 * A327248 A327249 A327250

Keyword

nonn

Author

Ilya Gutkovskiy, Sep 14 2019

Status

approved