id:A028991 - OEIS Search Results

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Odd 9-gonal (or enneagonal) numbers.

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1, 9, 75, 111, 261, 325, 559, 651, 969, 1089, 1491, 1639, 2125, 2301, 2871, 3075, 3729, 3961, 4699, 4959, 5781, 6069, 6975, 7291, 8281, 8625, 9699, 10071, 11229, 11629, 12871, 13299, 14625, 15081, 16491, 16975, 18469, 18981, 20559, 21099 (list; graph; listen)

	OFFSET	`0,2`
	LINKS	`Eric Weisstein's World of Mathematics, Source`
	FORMULA	`(1/2)[28n^2 + 4n + 1 + (14n+1)(-1)^n].`
	CROSSREFS	`Cf. A001106, A028992.` `Adjacent sequences: A028988 A028989 A028990 this_sequence A028992 A028993 A028994` `Sequence in context: A075232 A037533 A001716 this_sequence A102094 A125397 A095249`
	KEYWORD	`nonn`
	AUTHOR	`Patrick De Geest (pdg(AT)worldofnumbers.com)`

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Last modified May 11 10:28 EDT 2008. Contains 139662 sequences.

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