A182690 a(n) = the largest 2-digit number with exactly n divisors, a(n) = 0 if no such number exists.

0, 97, 49, 95, 81, 99, 64, 88, 36, 80, 0, 96, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

1,2

Links

Table of n, a(n) for n=1..50.

Formula

A000005(a(n)) = n for a(n) > 0.

12 = max n such that a(n) > 0, a(n) = 0 for n > 12.

Mathematica

With[{ds=Reverse[Table[{n, DivisorSigma[0, n]}, {n, 10, 99}]]}, Table[ SelectFirst[ ds, #[[2]]==k&], {k, 50}]][[All, 1]]/."NotFound"->0 (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 24 2019 *)

Crossrefs

Cf. A182689.

Sequence in context: A094498 A068830 A033417 * A088866 A244192 A075478

Adjacent sequences: A182687 A182688 A182689 * A182691 A182692 A182693

Keyword

nonn,base,less

Author

Jaroslav Krizek, Nov 27 2010

Status

approved