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A162964 a(n) = sigma(sigma(sigma(sigma(sigma(n))))). 1
1, 15, 24, 60, 120, 360, 168, 480, 168, 360, 360, 1170, 480, 1512, 1512, 210, 360, 1170, 728, 1680, 576, 480, 1512, 4800, 210, 1680, 1344, 3276, 992, 2016, 576, 1651, 1560, 3276, 1560, 1512, 1512, 4800, 3276, 4064, 1680, 5952, 1560, 5040, 4800, 2016, 1560, 5040 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences related to sigma(n)

FORMULA

a(n) = A000203(A000203(A000203(A000203(A000203(n))))).

MAPLE

with(numtheory); f:=n->sigma(sigma(sigma(sigma(sigma(n))))); [seq(f(n), n=1..100)];

MATHEMATICA

Table[Nest[DivisorSigma[1, #]&, n, 5], {n, 50}] (* Harvey P. Dale, Apr 19 2013 *)

PROG

(PARI) A162964(n) = sigma(sigma(sigma(sigma(sigma(n))))); \\ Antti Karttunen, Nov 18 2017

CROSSREFS

Cf. A000203, A129076, A066971, A051027.

Cf. also A049107.

Sequence in context: A089952 A295160 A240597 * A067343 A247315 A154150

Adjacent sequences:  A162961 A162962 A162963 * A162965 A162966 A162967

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jul 19 2009

EXTENSIONS

More terms from N. J. A. Sloane, Mar 20 2010

STATUS

approved

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Last modified September 18 15:48 EDT 2020. Contains 337169 sequences. (Running on oeis4.)