id:A070763 - OEIS Search Results

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Numbers n such that sigma(n) is a power of prime (of the form p^a, p prime, a>=1).

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2, 3, 4, 7, 9, 16, 21, 25, 31, 64, 81, 93, 127, 217, 289, 381, 400, 651, 729, 889, 1681, 2401, 2667, 3481, 3937, 4096, 5041, 7921, 8191, 10201, 11811, 15625, 17161, 24573, 27559, 27889, 28561, 29929, 57337, 65536, 82677, 83521, 85849 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`sigma(57337)=2^16 hence 57337 is in the sequence`
	PROGRAM	`(PARI) for(n=1, 100000, if(omega(sigma(n)) == 1, print1(n, ", ")))`
	CROSSREFS	`Sequence in context: A108809 A027947 A067236 this_sequence A071114 A078696 A098115` `Adjacent sequences: A070760 A070761 A070762 this_sequence A070764 A070765 A070766`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), May 14 2002`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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