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A178382 Primes that are in classes k+ and k- for some k in the Erdős-Selfridge classification of primes. 0

%I #3 Jan 03 2013 12:39:31

%S 2,3,5,7,17,29,41,43,61,79,101,131,137,149,173,197,211,223,227,229,

%T 233,239,241,251,271,281,293,307,311,331,353,397,439,449,463,523,569,

%U 593,607,641,683,691,727,733,751,761,787,821,853,859,919,947,953,983,1031

%N Primes that are in classes k+ and k- for some k in the Erdős-Selfridge classification of primes.

%C The first five terms are the only primes in both class 1+ and class 1-. The Mathematica program assigns 2 and 3 to class 0 in order to simplify the algorithm; they are actually in classes 1- and 1+.

%F Prime(n) such that A126433(n) = A126805(n).

%t classp[2]=0; classp[3]=0; SetAttributes[classp, Listable]; classp[p_] := classp[p] = 1+Max@@classp[First/@FactorInteger[p+1]]; classm[2]=0; classm[3]=0; SetAttributes[classm, Listable]; classm[p_] := classm[p] = 1+Max@@classm[First/@FactorInteger[p-1]]; Select[Prime[Range[1000]], classp[ # ]==classm[ # ]&]

%K nonn

%O 1,1

%A _T. D. Noe_, May 26 2010

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Last modified July 21 06:08 EDT 2024. Contains 374463 sequences. (Running on oeis4.)