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A070007 Arithmetical mean of distinct primes dividing n is a square number. 2
15, 42, 45, 65, 75, 77, 84, 87, 126, 135, 141, 168, 225, 247, 252, 258, 261, 285, 294, 301, 325, 335, 336, 357, 375, 378, 405, 410, 423, 429, 481, 504, 516, 539, 588, 589, 591, 618, 671, 672, 675, 717, 756, 767, 774, 783, 785, 820, 845, 847, 855, 882, 986 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Subset of A078174. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 20 2008]

EXAMPLE

n=1972=2.17.29: mean=(2+17+29)/3=48/3=16, a square.

CROSSREFS

Cf. A070005, A070006, A001414, A008472.

Sequence in context: A103003 A024845 A056698 * A154267 A173351 A051867

Adjacent sequences:  A070004 A070005 A070006 * A070008 A070009 A070010

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Apr 11 2002

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Last modified February 14 01:35 EST 2012. Contains 205567 sequences.