id:A121773 - OEIS Search Results

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

+0
2

1, 2, 6, 24, 165, 1560, 19684, 299600, 5381685, 111111340, 2593758618, 67546215528, 1941507500933, 61054982558024, 2085209014017960, 76861433640597376, 3041324492665174641, 128583032925805678368 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`a(n) is divisible by (n+1); a(n)/(n+1) = A121774(n).`
	FORMULA	`a(n) = (1/n)Sum_{d\|n} phi(n/d)(n+1)^d, 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))`
	CROSSREFS	`Cf. A121774, A056665.` `Sequence in context: A012715 A038205 A012361 this_sequence A012711 A073973 A034874` `Adjacent sequences: A121770 A121771 A121772 this_sequence A121774 A121775 A121776`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna (pauldhanna(AT)juno.com), Aug 20 2006`

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Last modified September 6 09:40 EDT 2008. Contains 143480 sequences.

AT&T Labs Research