A193348 - OEIS

A193348

Number of odd divisors of tau(n).

1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 2, 3

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OFFSET

1,4

LINKS

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

FORMULA

a(n) = A001227(A000005(n)). - Reinhard Zumkeller, Jul 25 2011

From Amiram Eldar, Aug 12 2024: (Start)

a(n) = 1 if and only if n is in A036537.

a(n) = A010553(n) if and only if n is a square. (End)

EXAMPLE

a(36) = 3 because tau(36) = 9 and the 3 odd divisors are {1, 3, 9}.