The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A125832 Numbers n which have exactly 14 representations as a product of two palindromes. 2

%I #4 Mar 30 2012 17:37:44

%S 5426124,8139186,20017998,21999978,26690664,26888862,29333304,

%T 49821684,73267326,97689768,98666568,146534652,147999852,220197978,

%U 271333062,274019262,320221902,403696293,471535064,489372884,516019504,518221704

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

%e 26888862 is in the sequence since 26888862 = 1*26888862 = 2*13444431

%e = 11*2444442 = 22*1222221 = 111*242242 = 121*222222 = 222*121121

%e = 242*111111 = 1001*26862 = 1221*22022 = 1331*20202 = 2002*13431

%e = 2442*11011 = 2662*10101.

%t 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}]

%Y Cf. A116993, A125833, A125834.

%K base,nonn

%O 1,1

%A _Farideh Firoozbakht_, Dec 10 2006

%E a(9)-a(22) from _Donovan Johnson_, Aug 05 2009

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 17 18:04 EDT 2024. Contains 373463 sequences. (Running on oeis4.)