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A005107 Class 3+ primes.
(Formerly M5261)
+0
23
37, 103, 113, 151, 157, 163, 173, 181, 193, 227, 233, 257, 277, 311, 331, 337, 347, 353, 379, 389, 397, 401, 409, 421, 457, 463, 467, 487, 491, 521, 523, 541, 547, 569, 571, 601, 607, 613, 631, 653, 683, 701, 727, 733, 773, 787, 797, 811, 821, 829, 853, 857 (list; graph; listen)
OFFSET

1,1

REFERENCES

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

MAPLE

For Maple program see Mathar link.

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]]; ClassPlusNbr[n_] := Length[ NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[150], ClassPlusNbr[ Prime[ # ]] == 3 &]]

CROSSREFS

Cf. A005113, A005105, A005106, A005108.

Adjacent sequences: A005104 A005105 A005106 this_sequence A005108 A005109 A005110

Sequence in context: A142941 A105019 A090496 this_sequence A139934 A142051 A033215

KEYWORD

nonn

AUTHOR

njas, Simon Plouffe (plouffe(AT)math.uqam.ca)

EXTENSIONS

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

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Last modified October 12 15:26 EDT 2008. Contains 144830 sequences.


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