A050769 Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 2 skipped primes.

10, 12, 14, 15, 21, 44, 90, 135, 210, 252, 294, 384, 468, 504, 513, 686, 704, 720, 768, 832, 864, 972, 1155, 1368, 1701, 1890, 2176, 2184, 2352, 2400, 2880, 3080, 3400, 3640, 3888, 4032, 4536, 4725, 5200, 6174, 6384, 8750, 9548, 10350, 10400, 10500

Offset

0,1

Links

Harvey P. Dale, Table of n, a(n) for n = 0..333 (all terms up to 5*10^6)

Example

a(6) = 44 + (2 + 2 + 11) = ending prime 59. Between 44 and 59 there are 2 primes: 47 and 53.

Mathematica

ckpgQ[n_]:=Module[{c=n+Total[Flatten[Table[#[[1]], {#[[2]]}]&/@ FactorInteger[ n]]]}, CompositeQ[n]&&PrimeQ[c]&&PrimePi[c]-PrimePi[n] == 3]; Select[Range[11000], ckpgQ] (* Harvey P. Dale, Nov 29 2014 *)

Crossrefs

Cf. A050703, A050710.

Sequence in context: A050705 A095406 A337028 * A330724 A351998 A088381

Adjacent sequences: A050766 A050767 A050768 * A050770 A050771 A050772

Keyword

nonn

Author

Patrick De Geest, Sep 15 1999

Status

approved