A163368 - OEIS

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A163368

phi(sigma(tau(n)))

1, 2, 2, 2, 2, 6, 2, 6, 2, 6, 2, 4, 2, 6, 6, 2, 2, 4, 2, 4, 6, 6, 2, 8, 2, 6, 6, 4, 2, 8, 2, 4, 6, 6, 6, 12, 2, 6, 6, 8, 2, 8, 2, 4, 4, 6, 2, 6, 2, 4 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`a(n) = A000010(A000203(A000005(n))) = A000010(A062069(n)) = A062401(A000005(n)).`
	FORMULA	`a(1) = 1, a(p) = 2 for p = primes (A000040), a(pq) = 6 for pq = product of two distinct primes (A006881), a(pq...z) = A000010(2^(k+1)-1) = A053287(k+1) for pq...z = product of k (k > 2) distinct primes p,q,...,z (A120944).`
	CROSSREFS	`Sequence in context: A198889 A130754 A164126 * A151948 A080400 A119462` `Adjacent sequences: A163365 A163366 A163367 * A163369 A163370 A163371`
	KEYWORD	`nonn`
	AUTHOR	`Jaroslav Krizek (jaroslav.krizek(AT)atlas.cz), Jul 25 2009`

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Last modified February 15 12:25 EST 2012. Contains 205786 sequences.