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A345278 a(n) = Sum_{p|n} p^(pi(p) mod 2). 1
0, 2, 1, 2, 5, 3, 1, 2, 1, 7, 11, 3, 1, 3, 6, 2, 17, 3, 1, 7, 2, 13, 23, 3, 5, 3, 1, 3, 1, 8, 31, 2, 12, 19, 6, 3, 1, 3, 2, 7, 41, 4, 1, 13, 6, 25, 47, 3, 1, 7, 18, 3, 1, 3, 16, 3, 2, 3, 59, 8, 1, 33, 2, 2, 6, 14, 67, 19, 24, 8, 1, 3, 73, 3, 6, 3, 12, 4, 1, 7, 1, 43, 83, 4, 22, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

a(15) = Sum_{p|15} p^(pi(p) mod 2) = 3^0 + 5^1 = 6.

MATHEMATICA

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

CROSSREFS

Cf. A000720 (pi), A345279.

Sequence in context: A216913 A124218 A025165 * A212431 A346517 A318354

Adjacent sequences:  A345275 A345276 A345277 * A345279 A345280 A345281

KEYWORD

nonn

AUTHOR

Wesley Ivan Hurt, Jun 12 2021

STATUS

approved

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Last modified December 2 05:01 EST 2021. Contains 349437 sequences. (Running on oeis4.)