login
A050777
First occurrence from iterated procedure 'composite k added to sum of its prime factors reaches a prime' yielding n skipped primes.
0
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
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
KEYWORD
nonn
AUTHOR
Patrick De Geest, Sep 15 1999
STATUS
approved