A361565 - OEIS

A361565

a(n) is the numerator of the median of divisors of n.

1, 3, 2, 2, 3, 5, 4, 3, 3, 7, 6, 7, 7, 9, 4, 4, 9, 9, 10, 9, 5, 13, 12, 5, 5, 15, 6, 11, 15, 11, 16, 6, 7, 19, 6, 6, 19, 21, 8, 13, 21, 13, 22, 15, 7, 25, 24, 7, 7, 15, 10, 17, 27, 15, 8, 15, 11, 31, 30, 8, 31, 33, 8, 8, 9, 17, 34, 21, 13, 17, 36, 17, 37, 39, 10

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OFFSET

1,2

LINKS

Winston de Greef, Table of n, a(n) for n = 1..10000

Index entries for sequences related to divisors of numbers

FORMULA

a(n) = numerator((A033676(n) + A033677(n))/2).

a(p) = (1 + p)/2 if p is an odd prime.

For p a prime, a(p^k) = (p^((k-1)/2) + p^((k+1)/2))/2 if k is odd, a(p^k) = p^(k/2) if k is even.

EXAMPLE

a(9) = 3 since the divisors of 9 are 1, 3, 9, and their median is 3.