A046453 Composite numbers with four prime factors (not necessarily distinct) whose concatenation yields a palindrome.

16, 81, 625, 2401, 3975, 4719, 5565, 6591, 8745, 10731, 14399, 14641, 16863, 20111, 34391, 36501, 39963, 41019, 46179, 47229, 48231, 60813, 61761, 62991, 69027, 109179, 113631, 116475, 143991, 158985, 159777, 162409, 164145, 167571, 183159, 184065

Offset: 1

Author

Patrick De Geest, Jul 15 1998

Keywords

• nonn
• base

Examples

			164145 = 3 * 5 * 31 * 353 -> 3531353 is palindromic.
		

Crossrefs

Intersection of A033993 and A046447.

Programs

Mathematica

pal4Q[n_]:=Module[{ds=Flatten[IntegerDigits/@(Table[First[#],{Last[ #]}]&/@ FactorInteger[n])]},PrimeOmega[n]==4&&ds==Reverse[ds]]; Select[ Range[190000],pal4Q] (* Harvey P. Dale, Nov 12 2011 *)

Extensions

One more term from Harvey P. Dale, Nov 12 2011