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A046355 Composite numbers with only palindromic prime factors whose sum is palindromic (counted with multiplicity).

%I A046355 #18 Oct 10 2019 22:53:06
%S A046355 4,6,8,9,10,12,14,15,16,18,20,24,27,28,40,45,48,54,121,308,440,495,
%T A046355 528,594,735,784,875,882,1050,1120,1250,1260,1331,1344,1500,1512,1600,
%U A046355 1701,1800,1920,2025,2048,2101,2121,2160,2304,2430,2525,2592,2751,2916,3030
%N A046355 Composite numbers with only palindromic prime factors whose sum is palindromic (counted with multiplicity).
%C A046355 Subsequence of the numbers k in A046349 such that A262049(k) is in A002113. - _R. J. Mathar_, Sep 09 2015
%H A046355 Giovanni Resta, <a href="/A046355/b046355.txt">Table of n, a(n) for n = 1..10000</a>
%e A046355 3030 = 2 * 3 * 5 * 101 -> 2 + 3 + 5 + 101 = 111 and 111 is a palindrome.
%p A046355 isA046355 := proc(n)
%p A046355     local sofpp ;
%p A046355     if isA046349(n) then
%p A046355         sofpp := A262049(n) ;
%p A046355         isA002113(sofpp) ;
%p A046355     else
%p A046355         false;
%p A046355     end if;
%p A046355 end proc:
%p A046355 for n from 2 to 400 do
%p A046355     if isA046355(n) then
%p A046355         printf("%d,",n);
%p A046355     end if;
%p A046355 end do: # _R. J. Mathar_, Sep 09 2015
%t A046355 palQ[n_] := Reverse[x=IntegerDigits[n]] == x; Select[Range[4,3100], !PrimeQ[#] && And@@palQ/@Join[{Total[Times@@@(x=FactorInteger[#])]}, First/@x]&] (* _Jayanta Basu_, Jun 05 2013 *)
%Y A046355 Cf. A046356, A046357.
%K A046355 nonn,base
%O A046355 1,1
%A A046355 _Patrick De Geest_, Jun 15 1998