A345279 a(n) = Sum_{p|n} p^((pi(p)+1) mod 2).

0, 1, 3, 1, 1, 4, 7, 1, 3, 2, 1, 4, 13, 8, 4, 1, 1, 4, 19, 2, 10, 2, 1, 4, 1, 14, 3, 8, 29, 5, 1, 1, 4, 2, 8, 4, 37, 20, 16, 2, 1, 11, 43, 2, 4, 2, 1, 4, 7, 2, 4, 14, 53, 4, 2, 8, 22, 30, 1, 5, 61, 2, 10, 1, 14, 5, 1, 2, 4, 9, 71, 4, 1, 38, 4, 20, 8, 17, 79, 2, 3, 2, 1, 11, 2, 44

Offset

1,3

Links

Table of n, a(n) for n=1..86.

Example

a(15) = Sum_{p|15} p^((pi(p)+1) mod 2) = 3^1 + 5^0 = 4.

Mathematica

Table[Sum[k^Mod[PrimePi[k] + 1, 2] (PrimePi[k] - PrimePi[k - 1]) (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 100}]

Crossrefs

Cf. A000720 (pi), A345278.

Sequence in context: A209172 A263950 A160870 * A342447 A025255 A296006

Adjacent sequences: A345276 A345277 A345278 * A345280 A345281 A345282

Keyword

nonn

Author

Wesley Ivan Hurt, Jun 12 2021

Status

approved