A226480 Squarefree numbers n such that (sopf(n)*d(n))^2 = sigma(n) where sopf(n) = sum of prime factors of n and d(n) = number of divisors of n.

22446139, 26116291, 28097023, 30236557, 31090489, 31124341, 49941589, 61137673, 62224039, 66960589, 71334867, 71585139, 82266591, 83045869, 92346023, 92837591, 105183961, 114762567, 123563821, 130399138, 131494219, 134156197, 134867722, 135095767, 136026037

Offset

1,1

Comments

Suggested by N. J. A. Sloane.

Links

Donovan Johnson, Table of n, a(n) for n = 1..500

Example

n = 22446139 = 31*67*101*107. sopf(n) = 31+67+101+107 = 306. d(n) = 16. (sopf(n)*d(n))^2 = (306*16)^2 = 23970816 = sigma(n).

Crossrefs

Cf. A000005, A000203, A006532, A008472, A126028, A226479.

Sequence in context: A046397 A226479 A126028 * A238154 A069377 A235931

Adjacent sequences: A226477 A226478 A226479 * A226481 A226482 A226483

Keyword

nonn

Author

Donovan Johnson, Jun 09 2013

Status

approved