A081426 Class 7- primes.

1439, 8629, 10067, 14683, 17257, 19577, 20389, 22643, 23743, 27103, 28219, 29399, 31657, 32633, 33107, 33113, 33863, 34259, 34513, 35951, 36137, 36887, 37379, 40127, 40637, 40759, 42179, 42209, 42767, 44519, 44579, 45139, 49019, 49669

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, A081425, 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[5200], ClassMinusNbr[ Prime[ # ]] == 7 &]]