A319246 Sum of prime indices of the n-th squarefree number.

0, 1, 2, 3, 3, 4, 4, 5, 6, 5, 5, 7, 8, 6, 6, 9, 7, 10, 6, 11, 7, 8, 7, 12, 9, 8, 13, 7, 14, 10, 15, 9, 16, 8, 10, 11, 17, 18, 12, 9, 8, 19, 11, 8, 20, 21, 13, 9, 9, 22, 14, 23, 10, 15, 12, 24, 10, 13, 16, 11, 25, 26, 10, 27, 9, 17, 28, 29, 9, 14, 30, 11, 12

Offset

1,3

Comments

A prime index of n is a number m such that prime(m) divides n.

Links

Table of n, a(n) for n=1..73.

Example

The 19th squarefree number is 30 with prime indices (3,2,1), so a(19) = 6.

Mathematica

Table[Total[Cases[FactorInteger[n], {p_, k_}:>k*PrimePi[p]]], {n, Select[Range[100], SquareFreeQ]}]

Crossrefs

Rows sums of A319247.

Cf. A000720, A001222, A005117, A056239, A072047, A265668, A299755, A299757, A319241, A319242.

Sequence in context: A182281 A218535 A306592 * A280026 A323080 A194806

Adjacent sequences: A319243 A319244 A319245 * A319247 A319248 A319249

Keyword

nonn

Author

Gus Wiseman, Sep 15 2018

Status

approved