id:A117285 - OEIS Search Results

Search: id:A117285

Displaying 1-1 of 1 results found.

page 1

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

+0
1

1, 2, 3, 5, 7, 11, 13, 17, 18, 19, 20, 22, 23, 25, 29, 30, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 75, 79, 83, 89, 97, 101, 102, 103, 107, 109, 110, 113, 127, 131, 132, 137, 139, 140, 149, 151, 155, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 203, 211, 223 (list; graph; listen)

	OFFSET	`0,2`
	EXAMPLE	`30 is in the sequence because 30-phi(30)=22, which is a pentagonal number.`
	CROSSREFS	`Cf. A000326.` `Adjacent sequences: A117282 A117283 A117284 this_sequence A117286 A117287 A117288` `Sequence in context: A084111 A020625 A033633 this_sequence A100546 A117094 A117289`
	KEYWORD	`nonn`
	AUTHOR	`Luc Stevens (lms022(AT)yahoo.com), Apr 23 2006`

page 1

Search completed in 0.002 seconds

Last modified October 13 18:37 EDT 2008. Contains 145008 sequences.

AT&T Labs Research