A070943 - OEIS

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A070943

Commuting elements: number of ordered pairs g, h in the group GL(2,Z_n) such that gh = hg.

1, 18, 384, 1344, 11520, 6912, 96768, 92160, 303264, 207360, 1584000, 516096, 4402944, 1741824, 4423680, 6094848, 22560768, 5458752, 44323200, 15482880, 37158912, 28512000, 141064704, 35389440, 186000000, 79252992, 226748160 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	FORMULA	`a(n) = A000252(n) * A062354(n) = n^4 * product (1-1/p^2)(1-1/p) sigma(n)*phi(n) ( where the product is over all the primes p that divide n ).`
	CROSSREFS	`Cf. A000252, A062354.` `Sequence in context: A182609 A086502 A099276 * A159647 A111454 A116421` `Adjacent sequences: A070940 A070941 A070942 * A070944 A070945 A070946`
	KEYWORD	`mult,nonn`
	AUTHOR	`Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 12 2003`
	EXTENSIONS	`More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 13 2003`

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Last modified February 13 16:02 EST 2012. Contains 205521 sequences.