id:A117287 - OEIS Search Results

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Numbers n for which the cototient n-phi(n) is a heptagonal number.

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1, 2, 3, 5, 7, 11, 13, 15, 17, 19, 23, 29, 31, 34, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 159, 163, 167, 173, 175, 179, 181, 189, 191, 193, 196, 197, 199, 208, 211, 223, 227, 229, 233 (list; graph; listen)

	OFFSET	`0,2`
	EXAMPLE	`49 is in the sequence because 49-phi(49)=7, which is a heptagonal number.`
	CROSSREFS	`Cf. A000566.` `Sequence in context: A102553 A069161 A003277 this_sequence A121615 A097605 A143578` `Adjacent sequences: A117284 A117285 A117286 this_sequence A117288 A117289 A117290`
	KEYWORD	`nonn`
	AUTHOR	`Luc Stevens (lms022(AT)yahoo.com), Apr 23 2006`

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Last modified November 18 20:14 EST 2008. Contains 147244 sequences.

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