OFFSET
1,1
LINKS
R. J. Mathar and Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 681 terms from R. J. Mathar)
FORMULA
EXAMPLE
15751 = 19 * 829 -> 19 + 829 = 848 and 848 is a palindrome.
MAPLE
n := 1 ;
for i from 3 to 30000 do
pal := A002113(i) ;
if not isprime(pal) then
sof := A001414(pal) ;
if isA002113(sof) then
printf("%d %d\n", n, pal) ;
n := n+1 ;
end if;
end if;
end do: # R. J. Mathar, Sep 09 2015
MATHEMATICA
palQ[n_]:=Reverse[x=IntegerDigits[n]]==x; Select[Range[4, 26170], !PrimeQ[#]&&And@@palQ/@{#, Total[Times@@@FactorInteger[#]]}&](* Jayanta Basu, Jun 05 2013 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jun 15 1998
STATUS
approved