A046348 Composite palindromes divisible by the sum of their prime factors (counted with multiplicity).

4, 646, 2772, 5445, 8778, 30303, 48384, 50505, 54145, 63336, 77077, 117711, 219912, 234432, 239932, 255552, 272272, 294492, 535535, 585585, 636636, 717717, 825528, 888888, 951159, 999999, 1103011, 1112111, 1345431, 2248422, 2267622

Offset

1,1

Links

David A. Corneth, Table of n, a(n) for n = 1..4180 (Terms <= 10^15. First 1000 terms from R. J. Mathar and Giovanni Resta)

David A. Corneth, PARI prog

Example

a(2)=646 :  2*17*19 -> 2 + 17 + 19 = 38 and 646 / 38 = 17.

Mathematica

t={}; Do[If[!PrimeQ[n]&&Reverse[x=IntegerDigits[n]]==x&&IntegerQ[n/Total[Times@@@FactorInteger[n]]], AppendTo[t, n]], {n, 4, 2.5*10^6}]; t (* Jayanta Basu, Jun 04 2013 *)
cpdQ[n_]:=CompositeQ[n]&&PalindromeQ[n]&&Divisible[n, Total[ Flatten[ Table[ #[[1]], #[[2]]]&/@FactorInteger[n]]]]; Select[Range[23*10^5], cpdQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 01 2018 *)

Prog

(PARI) See PARI link.

Crossrefs

Cf. A002113, A001414, A046346, A046347.

Sequence in context: A337650 A091288 A067171 * A332164 A334528 A183150

Adjacent sequences: A046345 A046346 A046347 * A046349 A046350 A046351

Keyword

nonn,base

Author

Patrick De Geest, Jun 15 1998

Status

approved