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A005110 Class 2- primes.
(Formerly M4783)
+0
14
11, 29, 31, 41, 43, 53, 61, 71, 79, 101, 103, 113, 127, 131, 137, 149, 151, 157, 181, 191, 197, 211, 223, 229, 239, 241, 251, 271, 281, 293, 307, 313, 337, 379, 389, 401, 409, 421, 439, 443, 449, 457, 491, 521, 541, 547, 571, 593, 601, 613, 631, 641, 647, 653, 673 (list; graph; listen)
OFFSET

1,1

REFERENCES

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

LINKS

R. J. Mathar, Table of n, a(n) for n = 1..13766

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[122], ClassMinusNbr[ Prime[ # ]] == 2 &] ] (* Robert G. Wilson v*)

CROSSREFS

Cf. A005113, A056637, A005109, A005111, A005112, A081424, A081425, A081426, A081427, A081428, A081429, A081430.

Sequence in context: A061086 A034276 A072711 this_sequence A059337 A126240 A124110

Adjacent sequences: A005107 A005108 A005109 this_sequence A005111 A005112 A005113

KEYWORD

nonn

AUTHOR

njas, Simon Plouffe (simon.plouffe(AT)gmail.com)

EXTENSIONS

Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Mar 20 2003

Corrected by R. J. Mathar, Feb 01 2007

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Last modified December 2 15:58 EST 2008. Contains 150992 sequences.


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