A073180 - OEIS

A073180

Number of divisors of n which are not greater than the squarefree kernel of n.

1, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 5, 2, 4, 4, 2, 2, 4, 2, 5, 4, 4, 2, 5, 2, 4, 2, 5, 2, 8, 2, 2, 4, 4, 4, 5, 2, 4, 4, 6, 2, 8, 2, 5, 5, 4, 2, 5, 2, 4, 4, 5, 2, 4, 4, 6, 4, 4, 2, 11, 2, 4, 5, 2, 4, 8, 2, 5, 4, 8, 2, 5, 2, 4, 4, 5, 4, 8, 2, 6, 2, 4, 2, 11, 4, 4, 4, 6, 2, 10, 4, 5, 4, 4, 4, 5, 2, 4, 5, 5, 2, 8, 2

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

OFFSET

1,2

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n) >= A034444(n).

a(n) = A095960(n) + 1. - Reinhard Zumkeller, Sep 10 2013

EXAMPLE

The squarefree kernel of 56 = 7*2^3 is 14 = 7*2 and the divisors <= 14 of 56 are {1, 2, 4, 7, 8, 14}, therefore a(56) = 6.

MATHEMATICA

a[n_] := DivisorSum[n, 1 &, # <= Times @@ FactorInteger[n][[;; , 1]] &]; Array[a, 100] (* Amiram Eldar, Jul 09 2022 *)