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A268863 a(n)=least number m such that gcd(prime(m)+2,prime(m+1)+2) = 2*n-1. 2

%I #5 Feb 27 2016 09:53:55

%S 1,11,61,350,180,1010,1933,1006,8555,4154,12089,9696,37932,14173,

%T 43447,39464,24706,129178,74854,59257,95206,531300,88480,1280569,

%U 934602,818760,85633,232992,2236506,953991,2768408,2225450

%N a(n)=least number m such that gcd(prime(m)+2,prime(m+1)+2) = 2*n-1.

%H Zak Seidov, <a href="/A268863/b268863.txt">Table of n, a(n) for n = 1..50</a>

%e n=1: m=1, p=prime(m)=2, q=prime(m+1)=3, gcd(p+2,q+2)=gcd(4,5)=1=2*1-1;

%e n=2: m=11, p=31, q=37, gcd(33,39)=3=2*2-1;

%e n=3: m=61, p=283, q=293, gcd(285, 295)=5=2*3-1;

%e n=50: m=15952683, p=294152659, q=294152857, gcd(294152661, 294152859)=99=2*50-1.

%K nonn

%O 1,2

%A _Zak Seidov_, Feb 15 2016

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Last modified April 17 01:50 EDT 2024. Contains 371756 sequences. (Running on oeis4.)