id:A117286 - OEIS Search Results

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

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1, 2, 3, 5, 7, 10, 11, 13, 17, 19, 23, 29, 31, 37, 39, 41, 43, 47, 52, 53, 55, 59, 61, 67, 71, 73, 79, 83, 89, 90, 97, 101, 103, 107, 109, 113, 117, 127, 129, 131, 137, 139, 149, 151, 157, 163, 167, 168, 173, 179, 181, 191, 193, 197, 199, 200, 205, 211, 223, 227, 229 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`55 is in the sequence because 55-phi(55)=15, which is a hexagonal number.`
	CROSSREFS	`Cf. A000384.` `Sequence in context: A048461 A058590 A064627 this_sequence A144726 A123885 A010062` `Adjacent sequences: A117283 A117284 A117285 this_sequence A117287 A117288 A117289`
	KEYWORD	`nonn`
	AUTHOR	`Luc Stevens (lms022(AT)yahoo.com), Apr 23 2006`
	EXTENSIONS	`Corrected by T. D. Noe (noe(AT)sspectra.com), Oct 25 2006`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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