id:A039766 - OEIS Search Results

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GCD(phi(a(n)),a(n)-1) = number of divisors of a(n).

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1

3, 21, 33, 57, 69, 77, 85, 93, 105, 125, 129, 141, 161, 175, 177, 201, 205, 209, 213, 221, 237, 249, 253, 309, 321, 329, 345, 365, 381, 393, 413, 417, 437, 445, 453, 473, 475, 485, 489, 493, 497, 501, 517, 533, 537, 565, 573, 581, 597, 629, 633, 649, 665 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`phi(21)=12, gcd(12,20)=4, 21 is divisible by {1,3,7,21}.`
	CROSSREFS	`Cf. A000005, A000010.` `Sequence in context: A091103 A045802 A006133 this_sequence A072849 A089323 A100986` `Adjacent sequences: A039763 A039764 A039765 this_sequence A039767 A039768 A039769`
	KEYWORD	`nonn,easy`
	AUTHOR	`Olivier Gerard (ogerard(AT)ext.jussieu.fr)`

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Last modified July 26 23:19 EDT 2008. Contains 142293 sequences.

AT&T Labs Research