

A067547


Number of divisors of n equals the average of distinct prime factors of n.


1



2, 9, 15, 114, 170, 175, 245, 351, 372, 558, 580, 625, 1012, 1032, 1375, 1377, 1450, 1640, 2322, 3944, 4225, 4240, 4700, 4824, 5566, 5766, 5929, 6432, 6591, 6655, 7236, 8272, 8385, 8410, 9933, 10250, 10545, 11152, 11193, 11638, 13209, 14973, 15168
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OFFSET

1,1


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


EXAMPLE

The prime factors of 15 are 3 and 5, having an average of 4. The number of divisors of 15 is also 4, so 15 is a term of the sequence.


MATHEMATICA

f[ n_ ] := FactorInteger[ n ]; g[ n_ ] := Module[ {a, l, t, r}, a = f[ n ]; l = Length[ a ]; t = Table[ a[ [ i ] ][ [ 1 ] ], {i, 1, l} ] ]; Select[ Range[ 2, 10^5 ], Mean[ g[ # ] ] == DivisorSigma[ 0, # ] & ]


CROSSREFS

Cf. A000005, A323171, A323172.
Sequence in context: A056724 A295732 A083174 * A166374 A083783 A162614
Adjacent sequences: A067544 A067545 A067546 * A067548 A067549 A067550


KEYWORD

nonn


AUTHOR

Joseph L. Pe, Jan 28 2002


EXTENSIONS

More terms from Naohiro Nomoto, Mar 01 2002


STATUS

approved



