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 A178997 Super-Poulet numbers having more than two different prime factors. 7

%I

%S 294409,1398101,1549411,1840357,12599233,13421773,15162941,15732721,

%T 28717483,29593159,61377109,66384121,67763803,74658629,78526729,

%U 90341197,96916279,109322501

%N Super-Poulet numbers having more than two different prime factors.

%C This is a subsequence of the super-Poulet numbers, A050217. Of the first 1000 super-Poulet numbers, only 18 have more than two prime factors.

%C a(10000) = A001567(5287334), so about 0.19% of the pseudoprimes in that range are in this sequence. - _Charles R Greathouse IV_, Sep 16 2016

%C The smallest Super-Poulet number with three prime factors not all distinct is 5654273717 = 4733*1093^2, which is not in this sequence. - _Emmanuel Vantieghem_, Sep 25 2018

%H Charles R Greathouse IV, <a href="/A178997/b178997.txt">Table of n, a(n) for n = 1..10000</a>

%H V. Shevelev, G. Garcia-Pulgarin, J. M. Velasquez and J. H. Castillo, <a href="http://arxiv.org/abs/1206.0606">Overpseudoprimes, and Mersenne and Fermat numbers as primover numbers</a>, arXiv preprint arXiv:1206:0606 [math.NT], 2012. - From _N. J. A. Sloane_, Oct 28 2012

%H V. Shevelev, G. García-Pulgarín, J. M. Velásquez-Soto and J. H. Castillo, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL15/Castillo/castillo2.html">Overpseudoprimes, and Mersenne and Fermat Numbers as Primover Numbers</a>, J. Integer Seq. 15 (2012) Article 12.7.7.

%t okQ[n_] := CompositeQ[n] && PrimeNu[n] > 2 && AllTrue[Divisors[n], PowerMod[2, #, n] == 2&];

%t Reap[For[n = 1, n < 10^8, n = n+2, If[okQ[n], Print[n]; Sow[n]]]][[2, 1]] (* _Jean-François Alcover_, Sep 11 2018 *) (* Corrected with PrimeNu instead of PrimeOmega by _Emmanuel Vantieghem_, Sep 24 2018 *)

%o (PARI) is(n)=my(f=factor(n)); if(#f~ < 3, return(0)); fordiv(f, d, if(Mod(2, d)^d!=2, return(0))); 1 \\ _Charles R Greathouse IV_, Sep 01 2016

%K nonn,more

%O 1,1

%A _T. D. Noe_, Jan 11 2011

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Last modified September 20 17:13 EDT 2020. Contains 337265 sequences. (Running on oeis4.)