A081425 Class 6- primes (for definition see A005109).

719, 1319, 1699, 2447, 3343, 4079, 4139, 4457, 4517, 4679, 4703, 5273, 5647, 6653, 6793, 7523, 7529, 7559, 8599, 9227, 9587, 9623, 9839, 10159, 10343, 10723, 10771, 11069, 11213, 11279, 11321, 11489, 11863, 11887, 12163, 12917, 12919, 13163

Offset: 1

Author

Robert G. Wilson v, Mar 20 2003

Keywords

• nonn

References

• R. K. Guy, Unsolved Problems in Number Theory, A18.

Links

• R. J. Mathar, Table of n, a(n) for n = 1..20000

Crossrefs

Cf. A005113, A056637, A005109, A005110, A005111, A005112, A081424, A081426, A081427, A081428, A081429, A081430.

Programs

Mathematica

PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] - 1]]; ClassMinusNbr[n_] := Length[NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[1700], ClassMinusNbr[ Prime[ # ]] == 6 &]]