A046352 Composite numbers whose sum of prime factors is palindromic (counted with multiplicity).

4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24, 27, 28, 40, 45, 48, 54, 57, 62, 85, 102, 106, 116, 121, 123, 182, 194, 218, 259, 260, 278, 292, 298, 305, 308, 312, 351, 358, 366, 370, 388, 403, 413, 415, 428, 440, 444, 483, 495, 498, 508, 528, 548, 568, 575, 590

Offset

1,1

Links

R. J. Mathar, Table of n, a(n) for n = 1..2014

Example

116 = 2 * 2 * 29 -> 2 + 2 + 29 = 33 and 33 is a palindrome.

Maple

n := 1 ;
for i from 2 to 30000 do
    if not isprime(i) then
        sof := A001414(i) ;
        if isA002113(sof) then
            printf("%d %d\n", n, i) ;
            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, 590], !PrimeQ[#]&&palQ[Total[Times@@@FactorInteger[#]]]&] (* Jayanta Basu, Jun 05 2013 *)
Select[Range@1000, CompositeQ@#&&PalindromeQ[Dot@@Transpose[FactorInteger@#]]&]  (* Hans Rudolf Widmer, Dec 21 2022 *)

Crossrefs

Cf. A046353, A046354.

Sequence in context: A199009 A070807 A246282 * A046355 A335419 A163122

Adjacent sequences: A046349 A046350 A046351 * A046353 A046354 A046355

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

Status

approved