A318995 - OEIS

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A318995

Totally additive with a(prime(n)) = n - 1.

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,5

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..10000

MAPLE

a:= n-> add((-1+numtheory[pi](i[1]))*i[2], i=ifactors(n)[2]):

seq(a(n), n=1..100); # Alois P. Heinz, Sep 07 2018

MATHEMATICA

Table[Cases[If[n==1, {}, FactorInteger[n]], {p_, k_}:>(PrimePi[p]-1)*k]//Total, {n, 200}]

PROG

(PARI) a(n)={my(f=factor(n)); sum(i=1, #f~, my([p, e]=f[i, ]); (primepi(p)-1)*e)} \\ Andrew Howroyd, Sep 07 2018