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Composite palindromes divisible by the palindromic sum of their prime factors (counted with multiplicity).
3

%I #17 Nov 24 2019 18:10:33

%S 4,5445,234432,585585,888888,951159,999999,1345431,2554552,4620264,

%T 5842485,6151516,9704079,12333321,40199104,42266224,42666624,44088044,

%U 46355364,63599536,63633636,420838024,424848424,631949136,649363946

%N Composite palindromes divisible by the palindromic sum of their prime factors (counted with multiplicity).

%e 649363946 = 2 * 7 * 11 * 83 * 101 * 503 -> Sum of factors is palindrome 707 -> 649363946 / 707 = 918478 exactly.

%t palQ[n_]:= Reverse[x=IntegerDigits[n]] == x; t={}; Do[If[!PrimeQ[n] && And@@palQ/@{n,y=Total[Times@@@FactorInteger[n]]} && IntegerQ[n/y], AppendTo[t,n]],{n, 4, 6*10^6}]; t (* _Jayanta Basu_, Jun 05 2013 *)

%t pspfQ[n_]:=Module[{sf=Total[Times@@@FactorInteger[n]]},CompositeQ[ n] && AllTrue[{n,sf},PalindromeQ]&&IntegerQ[n/sf]]; Select[Range[ 2,65*10^7], pspfQ] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 24 2019 *)

%Y Cf. A046358, A046359.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jun 15 1998

%E Definition clarified by _Harvey P. Dale_, Nov 24 2019