cp's OEIS Frontend

A046354 Composite palindromes whose sum of prime factors is palindromic (counted with multiplicity).

%I A046354 #16 Oct 10 2019 22:53:22
%S A046354 4,6,8,9,121,292,444,575,717,828,989,1331,2002,4884,5445,8668,9559,
%T A046354 10201,11211,11811,13231,14241,14541,14641,15251,15751,16261,16761,
%U A046354 18281,19291,19591,20002,21112,21312,22022,22922,23832,26062,26162
%N A046354 Composite palindromes whose sum of prime factors is palindromic (counted with multiplicity).
%H A046354 R. J. Mathar and Giovanni Resta, <a href="/A046354/b046354.txt">Table of n, a(n) for n = 1..10000</a> (first 681 terms from R. J. Mathar)
%F A046354 A046352 INTERSECT A002113. - _R. J. Mathar_, Sep 09 2015
%e A046354 15751 = 19 * 829 -> 19 + 829 = 848 and 848 is a palindrome.
%p A046354 n := 1 ;
%p A046354 for i from 3 to 30000 do
%p A046354     pal := A002113(i) ;
%p A046354     if not isprime(pal) then
%p A046354         sof := A001414(pal) ;
%p A046354         if isA002113(sof) then
%p A046354             printf("%d %d\n",n,pal) ;
%p A046354             n := n+1 ;
%p A046354         end if;
%p A046354     end if;
%p A046354 end do: # _R. J. Mathar_, Sep 09 2015
%t A046354 palQ[n_]:=Reverse[x=IntegerDigits[n]]==x; Select[Range[4,26170],!PrimeQ[#]&&And@@palQ/@{#,Total[Times@@@FactorInteger[#]]}&](* _Jayanta Basu_, Jun 05 2013 *)
%Y A046354 Cf. A046352, A046353.
%K A046354 nonn,base
%O A046354 1,1
%A A046354 _Patrick De Geest_, Jun 15 1998