A125832 Numbers n which have exactly 14 representations as a product of two palindromes.

5426124, 8139186, 20017998, 21999978, 26690664, 26888862, 29333304, 49821684, 73267326, 97689768, 98666568, 146534652, 147999852, 220197978, 271333062, 274019262, 320221902, 403696293, 471535064, 489372884, 516019504, 518221704

Offset

1,1

Links

Table of n, a(n) for n=1..22.

Example

26888862 is in the sequence since 26888862 = 1*26888862 = 2*13444431
= 11*2444442 = 22*1222221 = 111*242242 = 121*222222 = 222*121121
= 242*111111 = 1001*26862 = 1221*22022 = 1331*20202 = 2002*13431
= 2442*11011 = 2662*10101.

Mathematica

f[n_]:=f[n]=Length[Select[Divisors[n], #<=n^(1/2)&&FromDigits[ Reverse[IntegerDigits[ # ]]]==#&&FromDigits[Reverse[IntegerDigits [n/# ]]]==n/#&]]; Do[If[f[n]==14, Print[n]], {n, 50000000}]

Crossrefs

Cf. A116993, A125833, A125834.

Sequence in context: A092020 A029822 A263214 * A206325 A203549 A230793

Adjacent sequences: A125829 A125830 A125831 * A125833 A125834 A125835

Keyword

base,nonn

Author

Farideh Firoozbakht, Dec 10 2006

Extensions

a(9)-a(22) from Donovan Johnson, Aug 05 2009

Status

approved