A062553 - OEIS

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A062553

Number of Abelian subgroups of dihedral group with 2n elements.

2, 5, 5, 9, 7, 13, 9, 16, 12, 19, 13, 24, 15, 25, 19, 29, 19, 33, 21, 36, 25, 37, 25, 44, 28, 43, 31, 48, 31, 53, 33, 54, 37, 55, 39, 63, 39, 61, 43, 68, 43, 71, 45, 72, 51, 73, 49, 82, 52, 81, 55, 84, 55, 89, 59, 92, 61, 91, 61, 102, 63, 97, 69, 103, 69, 107, 69, 108, 73 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,1`
	FORMULA	`a(n) = n+tau(n) if n is odd, 3/2*n+tau(n) if n is even, where tau(n)=the number of divisors of n, cf. A000005.`
	CROSSREFS	`Cf. A062249, A007503.` `Sequence in context: A145420 A152781 A200242 * A126357 A070243 A050175` `Adjacent sequences: A062550 A062551 A062552 * A062554 A062555 A062556`
	KEYWORD	`nonn`
	AUTHOR	`Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 02 2001`
	EXTENSIONS	`Formula and more terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 05 2001`

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Last modified February 14 17:33 EST 2012. Contains 205644 sequences.