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

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Last modified June 24 12:30 EDT 2021. Contains 345416 sequences. (Running on oeis4.)