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A005108 Class 4+ primes (for definition see A005105).
(Formerly M5350)
24

%I M5350 #22 Jan 13 2014 11:56:19

%S 73,313,443,617,661,673,677,691,739,757,823,887,907,941,977,1093,1109,

%T 1129,1201,1213,1303,1361,1447,1453,1543,1553,1621,1627,1657,1753,

%U 1811,1867,1873,1993,1997,2017,2081,2083,2113,2269,2273,2281,2293,2333,2341

%N Class 4+ primes (for definition see A005105).

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

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%H T. D. Noe, <a href="/A005108/b005108.txt">Table of n, a(n) for n=1..10000</a>

%p For Maple program see Mathar link in A005105.

%t 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[350], ClassPlusNbr[ Prime[ # ]] == 4 &]]

%Y Cf. A005113, A005105, A005106, A005107.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, _Simon Plouffe_

%E Edited and extended by _Robert G. Wilson v_, Mar 20 2003

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Last modified March 29 08:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)