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A163378 a(n) = sigma(phi(tau(n))). 3
1, 1, 1, 3, 1, 3, 1, 3, 3, 3, 1, 3, 1, 3, 3, 7, 1, 3, 1, 3, 3, 3, 1, 7, 3, 3, 3, 3, 1, 7, 1, 3, 3, 3, 3, 12, 1, 3, 3, 7, 1, 7, 1, 3, 3, 3, 1, 7, 3, 3, 3, 3, 1, 7, 3, 7, 3, 3, 1, 7, 1, 3, 3, 12, 3, 7, 1, 3, 3, 7, 1, 7, 1, 3, 3, 3, 3, 7, 1, 7, 7, 3, 1, 7, 3, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = A000203(A000010(A000005(n))) = A000203(A163109(n)) = A062402(A000005(n)).

MATHEMATICA

Table[DivisorSigma[1, EulerPhi[DivisorSigma[0, n]]], {n, 100}] (* Harvey P. Dale, Jun 21 2016 *)

PROG

(PARI) vector(100, n, sigma(eulerphi(numdiv(n)))) \\ G. C. Greubel, Dec 20 2016

CROSSREFS

Cf. A000005, A000010, A000203, A062402, A163109.

Sequence in context: A255894 A135023 A087822 * A025810 A001319 A240833

Adjacent sequences:  A163375 A163376 A163377 * A163379 A163380 A163381

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jul 25 2009

EXTENSIONS

More terms from Harvey P. Dale, Jun 21 2016

STATUS

approved

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Last modified August 4 19:21 EDT 2020. Contains 336202 sequences. (Running on oeis4.)