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%I #20 Jan 27 2019 02:59:07
%S 1,1,1,2,2,1,3,4,2,6,3,1,4,12,6,2,8,9,3,12,4,16,18,6,24,27,1,32,36,12,
%T 48,54,2,64,72,81,3,96,108,4,128,144,162,6,192,216,8,1,9,288,324,12,
%U 384,432,16,2,18,576,648,24,3,27,864,32,4,36,1152,1296,48,6,54,1728,64,8,72,9,81,2592,96,12
%N Greatest common divisor of the n-th and (n+1)st 3-smooth numbers.
%C A186712 shows where this function and the 3-smooth numbers A003586 are in the same range: a(A186712(n)) = A003586(n) and a(m) != A003586(n) for m < A186712(n).
%H Reinhard Zumkeller, <a href="/A186711/b186711.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A050873(A003586(n+1), A003586(n)).
%F a(A186771(n)) = 1.
%p A186711 := proc(n) igcd(A003586(n),A003586(n+1)) ; end proc: # _R. J. Mathar_, Feb 28 2011
%t S3 = Select[Range[3*10^4], FactorInteger[#][[-1, 1]] <= 3&]; Table[GCD[ S3[[n]], S3[[n+1]] ], {n, 1, Length[S3]-1}] (* _Jean-François Alcover_, Feb 02 2018 *)
%o (Haskell)
%o a186711 n = a186711_list !! (n-1)
%o a186711_list = zipWith gcd a003586_list $ tail a003586_list
%Y Cf. A003586, A050873, A061987, A186771.
%K nonn
%O 1,4
%A _Reinhard Zumkeller_, Feb 26 2011
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