A369747 a(n) = Sum_{p|n, p prime} pi(n/p).

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

Offset

1,6

Links

Table of n, a(n) for n=1..81.

Formula

a(p^k) = pi(p^(k-1)), for p prime and k >= 1. - Wesley Ivan Hurt, Jun 26 2024

Mathematica

Table[DivisorSum[n, PrimePi[n/#] &, PrimeQ[#] &], {n, 100}]

Crossrefs

Cf. A000040, A000720 (pi), A062774, A345301, A369745.

Sequence in context: A326395 A290566 A285006 * A300722 A087625 A300720

Adjacent sequences: A369744 A369745 A369746 * A369748 A369749 A369750

Keyword

nonn,easy

Author

Wesley Ivan Hurt, Jan 30 2024

Status

approved