A050768 Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 1 skipped prime.

6, 20, 48, 112, 320, 1326, 1400, 4165, 4374, 10395, 12852, 15827, 20412, 23232, 24300, 24990, 25000, 27200, 27300, 31407, 33660, 34965, 38480, 41553, 42525, 50688, 53508, 65450, 66000, 68400, 69498

Offset

0,1

Links

Table of n, a(n) for n=0..30.

Example

a(2)=20 + (2+2+5) = ending prime 29. Between 20 and 29 lies exactly one prime 23.

Mathematica

aQ[n_]:=NextPrime[NestWhile[#+Total[Times@@@FactorInteger[#]]&, n, !PrimeQ[#]&], -1]==NextPrime[n]; Select[Range[70000], !PrimeQ[#]&&aQ[#]&] (* Jayanta Basu, May 31 2013 *)

Crossrefs

Cf. A050703, A050710.

Sequence in context: A055455 A203552 A331754 * A161438 A063488 A299292

Adjacent sequences: A050765 A050766 A050767 * A050769 A050770 A050771

Keyword

nonn

Author

Patrick De Geest, Sep 15 1999

Status

approved