

A243220


Number of divisors of A002183(n).


3



1, 2, 2, 3, 4, 4, 3, 4, 6, 5, 6, 6, 8, 8, 6, 9, 8, 10, 12, 7, 12, 10, 12, 12, 12, 9, 12, 16, 8, 15, 12, 16, 18, 14, 12, 16, 12, 20, 9, 18, 14, 20, 24, 16, 15, 20, 14, 24, 24, 10, 21, 24, 16, 24, 30, 18, 18, 24, 16, 28, 30, 11, 24, 30, 18, 28, 36, 20, 21, 40, 28, 18, 32, 36, 12, 27, 36, 32, 42, 22, 48, 32, 20, 45, 36, 42, 13, 48, 30, 42, 60, 36, 48
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OFFSET

1,2


REFERENCES

S. Ramanujan, Collected Papers, Ed. G. H. Hardy et al., Cambridge 1927; Chelsea, NY, 1962, p. 87.


LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000


FORMULA

a(n) = A000005(A000005(A002182(n))).  Michel Marcus, Oct 08 2016


MATHEMATICA

(* This program is not suitable to compute a large number of terms. *) Reap[For[record = 0; n = 1, n <= 10^9, n = If[n < 60, n + 1, n + 60], tau = DivisorSigma[0, n]; If[tau > record, record = tau; t = DivisorSigma[0, tau]; Print[t]; Sow[t]]]][[2, 1]] (* JeanFrançois Alcover, Oct 08 2016 *)


CROSSREFS

Cf. A000005, A002183, A002182.
Sequence in context: A274061 A284009 A326846 * A334593 A293596 A301977
Adjacent sequences: A243217 A243218 A243219 * A243221 A243222 A243223


KEYWORD

nonn,look


AUTHOR

N. J. A. Sloane, Jun 01 2014


STATUS

approved



