A046450 Concatenation of prime factors of palindromic composite is a palindrome.

4, 8, 9, 121, 343, 1331, 10001, 10201, 14641, 36763, 1030301, 1037301, 1226221, 9396939, 104060401, 12467976421, 14432823441, 93969696939, 119092290911, 1030507050301, 1120237320211, 1225559555221, 1234469644321, 1334459544331, 100330272033001, 101222252222101

Offset

1,1

Links

Table of n, a(n) for n=1..26.

Example

E.g., 14432823441 = 3 * 3 * 281 * 313 * 18233 -> 3328131318233 is palindromic.

Mathematica

d[n_] := IntegerDigits[n]; co[n_, k_] := Nest[Flatten[d[{#, n}]] &, n, k - 1]; t = {}; Do[If[! PrimeQ[n] && Reverse[x = d[n]] == x && Reverse[y = Flatten[d[co @@@ FactorInteger[n]]]] == y, AppendTo[t, n]], {n, 2, 10^7}]; t (* Jayanta Basu, Jun 24 2013 *)

Crossrefs

Cf. A046447, A046448, A046449.

Sequence in context: A128827 A075786 A348429 * A077271 A084093 A072037

Adjacent sequences: A046447 A046448 A046449 * A046451 A046452 A046453

Keyword

nonn,base

Author

Patrick De Geest, Jul 15 1998

Extensions

Corrected by Charles R Greathouse IV, Apr 23 2010

a(18)-a(24) from Donovan Johnson, May 03 2010

a(25)-a(26) from Donovan Johnson, Aug 09 2011

Status

approved