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
Keywords
Examples
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.
Links
- C. Rivera, Puzzle 66 - The SOPF sequences
Programs
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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 *)