A273353 Number of divisors of A067128(n).

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

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, n-1, if(numdiv(k) > nd, return(0))); return(1)
for(n=1, 50000, if(is_a067128(n), print1(numdiv(n), ", "))) \\ Felix Fröhlich, May 24 2016

Crossrefs

Cf. A000005, A002182, A002183, A034287, A067128.

Sequence in context: A309965 A366385 A070172 * A367410 A259197 A309559

Adjacent sequences: A273350 A273351 A273352 * A273354 A273355 A273356

Keyword

nonn

Author

David A. Corneth, May 20 2016

Status

approved