A050777 First occurrence from iterated procedure 'composite k added to sum of its prime factors reaches a prime' yielding n skipped primes.

38400, 6, 10, 26, 8, 18, 4, 39, 16, 30, 27, 32, 126, 76, 92, 87, 63, 77, 122, 49, 62, 120, 56, 50, 45, 117, 110, 196, 88, 102, 75, 246, 171, 72, 70, 234, 60, 469, 66, 217, 260, 198, 244, 387, 550, 230, 528, 362, 519, 764, 500, 494, 566, 376, 548, 386, 526, 481

Offset

0,1

Links

Table of n, a(n) for n=0..57.

C. Rivera, Puzzle 66 - The SOPF sequences

Example

a(1)=38400 + (2+2+2+2+2+2+2+2+2+3+5+5) = 38431. '0' primes between 38400 and 38431.
a(2)=6 + (2+3) = 11. '1' prime between 6 and 11.
a(3)=10 + (2+5) = 17. '2' primes between 10 and 17.

Mathematica

a[n_]:=Length[Select[Range[n+1, NestWhile[#+Total[Times@@@FactorInteger[#]]&, n, !PrimeQ[#]&]-1], PrimeQ]]; t={38400}; Do[i=4; While[a[i]!=k, If[PrimeQ[i+1], i+=2, i++]]; AppendTo[t, i], {k, 57}]; t (* Jayanta Basu, Jun 01 2013 *)

Crossrefs

Cf. A050765, A050768-A050776, A050703.

Sequence in context: A138400 A248690 A342960 * A050765 A254852 A203792

Adjacent sequences: A050774 A050775 A050776 * A050778 A050779 A050780

Keyword

nonn

Author

Patrick De Geest, Sep 15 1999

Status

approved