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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
OFFSET
1,2
FORMULA
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. also A049107.
Sequence in context: A373406 A295160 A240597 * A067343 A247315 A154150
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jul 19 2009
EXTENSIONS
More terms from N. J. A. Sloane, Mar 20 2010
STATUS
approved