%I A067605
%S A067605 2,6,11,24,42,121,30,319,99,1592,344,574,3786,4196,650,4619,217,1532,
%T A067605 11244,5349,8081,3861,12751,18281,9221,5995,22467,16222,43969,35975,
%U A067605 192603,108146,52313,218234,15927,132997,42673,78858,103865,84483
%N A067605 Least k such that the GCD( prime(k+1)-1, prime(k)-1 ) = 2n.
%C A067605 Since all consecutive primes, p < q and p greater than 2, are odd, therefore 
               the GCD( p-1, q-1 ) must be even.
%e A067605 n=4: a(4)=24=GCD[89-1,97-1]=GCD[p(24)-1,p(25)-1]=8=2n.
%t A067605 a = Table[0, {100}]; p = 3; q = 5; Do[q = Prime[n + 1]; d = GCD[p - 1, 
               q - 1]/2; If[d < 101 && a[[d]] == 0, a[[d]] = n]; b = c, {n, 2, 10^7}]; 
               a
%Y A067605 Cf. A063444, A084307, A058263.
%Y A067605 Sequence in context: A103143 A005673 A084308 this_sequence A072986 A160966 
               A079047
%Y A067605 Adjacent sequences: A067602 A067603 A067604 this_sequence A067606 A067607 
               A067608
%K A067605 easy,nonn
%O A067605 1,1
%A A067605 Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 31 2002