OFFSET
1,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
EXAMPLE
E.g., 81 = 3 * 3 * 3 * 3 -> 3333 is palindromic.
MATHEMATICA
concat[n_]:=Flatten[Table[IntegerDigits[First[n]], {Last[n]}]]; palQ[n_]:= Module[{x=Flatten[concat/@FactorInteger[n]]}, x==Reverse[x]&&!PrimeQ[n]]; Select[Range[2500], palQ] (* Harvey P. Dale, May 24 2011 *)
PROG
(Haskell)
a046447 n = a046447_list !! (n-1)
a046447_list = 1 : filter f [1..] where
f x = length ps > 1 && ps' == reverse ps'
where ps' = concatMap show ps; ps = a027746_row x
-- Reinhard Zumkeller, May 02 2014
(Python)
from sympy import factorint, isprime
A046447_list = [1]
for n in range(4, 10**6):
....if not isprime(n):
........s = ''.join([str(p)*e for p, e in sorted(factorint(n).items())])
........if s == s[::-1]:
............A046447_list.append(n) # Chai Wah Wu, Jan 03 2015
CROSSREFS
KEYWORD
nonn,nice,base
AUTHOR
Patrick De Geest, Jul 15 1998
STATUS
approved