

A273353


Number of divisors of A067128(n).


2



1, 2, 2, 3, 4, 4, 4, 6, 6, 6, 8, 8, 9, 10, 12, 12, 12, 12, 12, 12, 16, 16, 18, 20, 20, 24, 24, 24, 24, 24, 24, 24, 24, 24, 30, 32, 32, 36, 36, 40, 40, 48, 48, 48, 48, 48, 48, 48, 48, 60, 64, 64, 72, 72, 72, 80, 80, 84, 90, 96, 96, 96, 96, 96, 96, 96, 96, 96, 100, 108, 120, 120, 120, 128, 128, 144, 144, 144, 144, 144, 160
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OFFSET

1,2


COMMENTS

Is a(n + 1) / a(n) ~ 1 for large n?
Every term in this sequence also appears in A002183, where every element of this sequence occurs exactly once.
In A067128 it is asked if A034287 = A067128. If that is the case then this sequence is also the number of divisors of A034287.


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


FORMULA

a(n) = A000005(A067128(n)).


MATHEMATICA

s = {}; dmax = 0; Do[d = DivisorSigma[0, n]; If[d >= dmax, AppendTo[s, d]; dmax = d], {n, 1, 10^6}]; s (* Amiram Eldar, Jun 07 2019 *)


PROG

(PARI) is_a067128(n) = my(nd=numdiv(n)); for(k=1, n1, if(numdiv(k) > nd, return(0))); return(1)
for(n=1, 50000, if(is_a067128(n), print1(numdiv(n), ", "))) \\ Felix FrÃ¶hlich, May 24 2016


CROSSREFS

Cf. A000005, A002182, A002183, A034287, A067128.
Sequence in context: A224709 A309965 A070172 * A259197 A130128 A210556
Adjacent sequences: A273350 A273351 A273352 * A273354 A273355 A273356


KEYWORD

nonn


AUTHOR

David A. Corneth, May 20 2016


STATUS

approved



