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A046354 Composite palindromes whose sum of prime factors is palindromic (counted with multiplicity). 3

%I

%S 4,6,8,9,121,292,444,575,717,828,989,1331,2002,4884,5445,8668,9559,

%T 10201,11211,11811,13231,14241,14541,14641,15251,15751,16261,16761,

%U 18281,19291,19591,20002,21112,21312,22022,22922,23832,26062,26162

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

%H 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 A046352 INTERSECT A002113. - _R. J. Mathar_, Sep 09 2015

%e 15751 = 19 * 829 -> 19 + 829 = 848 and 848 is a palindrome.

%p n := 1 ;

%p for i from 3 to 30000 do

%p pal := A002113(i) ;

%p if not isprime(pal) then

%p sof := A001414(pal) ;

%p if isA002113(sof) then

%p printf("%d %d\n",n,pal) ;

%p n := n+1 ;

%p end if;

%p end if;

%p end do: # _R. J. Mathar_, Sep 09 2015

%t palQ[n_]:=Reverse[x=IntegerDigits[n]]==x; Select[Range[4,26170],!PrimeQ[#]&&And@@palQ/@{#,Total[Times@@@FactorInteger[#]]}&](* _Jayanta Basu_, Jun 05 2013 *)

%Y Cf. A046352, A046353.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jun 15 1998.

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Last modified February 16 12:48 EST 2019. Contains 320163 sequences. (Running on oeis4.)