id:A121774 - OEIS Search Results

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Number of n-bead necklaces with n+1 colors, divided by (n+1), for n>0, with a(0)=1.

+0
2

1, 1, 2, 6, 33, 260, 2812, 37450, 597965, 11111134, 235796238, 5628851294, 149346730841, 4361070182716, 139013934267864, 4803839602537336, 178901440745010273, 7143501829211426576, 304465936544543927890 (list; graph; listen)

	OFFSET	`0,3`
	FORMULA	`a(n) = (1/n)Sum_{d\|n} phi(n/d)(n+1)^(d-1), for n>0, with a(0)=1.`
	PROGRAM	`(PARI) a(n)=if(n==0, 1, (1/n)sumdiv(n, d, eulerphi(n/d)(n+1)^(d-1)))`
	CROSSREFS	`Cf. A121773, A056665.` `Sequence in context: A127114 A138909 A138983 this_sequence A053042 A012874 A005161` `Adjacent sequences: A121771 A121772 A121773 this_sequence A121775 A121776 A121777`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Aug 20 2006`

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

AT&T Labs Research