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 A163105 a(n) = tau(sigma(tau(n))), where tau = number of divisors of n (A000005), and sigma = sum of divisors of n (A000203). 1
 1, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 6, 2, 2, 2, 4, 2, 6, 2, 6, 2, 2, 2, 4, 3, 2, 2, 6, 2, 4, 2, 6, 2, 2, 2, 2, 2, 2, 2, 4, 2, 4, 2, 6, 6, 2, 2, 6, 3, 6, 2, 6, 2, 4, 2, 4, 2, 2, 2, 6, 2, 2, 6, 4, 2, 4, 2, 6, 2, 4, 2, 6, 2, 2, 6, 6, 2, 4, 2, 6, 4, 2, 2, 6, 2, 2, 2, 4, 2, 6, 2, 6, 2, 2, 2, 6, 2, 6, 6, 2, 2, 4, 2, 4, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Repeated application of tau (number of divisors) and sigma (sum of divisors). LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A000005(A000203(A000005(n))) = A000005(A062069(n)) = A062068(A000005((n)). MAPLE with(numtheory) : A163105 := proc(n) tau(sigma(tau(n))) ; end: seq(A163105(n), n=1..120) ; # R. J. Mathar, Jul 27 2009 PROG (PARI) A163105(n) = numdiv(sigma(numdiv(n))); \\ Antti Karttunen, Jul 23 2017 CROSSREFS Cf. A000005, A000203, A062068, A062069, A163106. Sequence in context: A134852 A071188 A078545 * A152235 A278966 A123582 Adjacent sequences:  A163102 A163103 A163104 * A163106 A163107 A163108 KEYWORD nonn AUTHOR Jaroslav Krizek, Jul 20 2009 EXTENSIONS More terms from R. J. Mathar, Jul 27 2009 Name edited by Antti Karttunen, Jul 23 2017 STATUS approved

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Last modified December 15 17:03 EST 2019. Contains 330000 sequences. (Running on oeis4.)