A087997 a(n) is the least number with n palindromic divisors.

1, 2, 4, 6, 12, 24, 72, 66, 484, 132, 616, 264, 2112, 792, 1848, 2772, 7326, 8712, 5544, 13332, 14652, 24024, 36036, 26664, 87912, 102564, 72072, 79992, 186648, 205128, 360360, 279972, 264264, 666666, 1213212, 879912, 559944, 888888, 792792

Offset: 1

Author

Labos Elemer, Oct 13 2003

Keywords

• base
• nonn

Examples

			n=24: a(24)=26664 has 32 divisors of which 24 are palindromic numbers: {1, 2, 3, 4, 6, 8, 11, 22, 33, 44, 66, 88, 101, 202, 303, 404, 606, 808, 1111, 2222, 3333, 4444, 6666, 8888}.
Some solutions are palindromic (like 2112), some are not (like 132).
		

Links

• Donovan Johnson, Table of n, a(n) for n = 1..150

Crossrefs

Cf. A087990.

Programs

Mathematica

t = Table[Count[Divisors[k], ?(Reverse[x = IntegerDigits[#]] == x &)], {k, 2,15*10^5, 2}]; Join[{1}, Table[i = 1; While[t[[i]] != k, i++]; 2 i, {k, 2, 39}]] (* _Jayanta Basu, Aug 12 2013 *)
Module[{pds=Table[{n,Count[Divisors[n],?PalindromeQ]},{n,1214000}]},Table[ SelectFirst[pds,#[[2]]==k&],{k,39}]][[All,1]] (* _Harvey P. Dale, Dec 17 2021 *)

Formula

a(n)=Min{x; A087990[x]=n}

Extensions

More terms from Ray Chandler, Oct 17 2003