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A046352
Composite numbers whose sum of prime factors is palindromic (counted with multiplicity).
4
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
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
Sequence in context: A070807 A246282 A374954 * A046355 A335419 A163122
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jun 15 1998
STATUS
approved