%I #4 Sep 30 2014 15:57:13
%S 1,3,4,6,7,8,10,11,12,14,15,17,18,19,21,22,24,25,26,28,29,31,32,33,35,
%T 36,38,39,40,42,43,45,46,47,49,50,51,53,54,56,57,58,60,61,63,64,65,67,
%U 68,70,71,72,74,75,77,78,79,81,82,83,85,86,88,89,90,92
%N Numbers k such that A247985(k+1) - A247985(k) = 3.
%C Complement of A247986.
%H Clark Kimberling, <a href="/A247987/b247987.txt">Table of n, a(n) for n = 1..1000</a>
%t z = 100; p[k_] := p[k] = Product[(k^2 + h)/(k^2 - h), {h, 1, k}] (* Finch p. 14 *)
%t N[Table[p[n] - E, {n, 2, z}]]
%t f[n_] := f[n] = Select[1 + Range[z], p[#] - E < 1/n &, 1];
%t u = Flatten[Table[f[n], {n, 1, z}]] ; (* A247985 *)
%t v = Differences[u];
%t Flatten[Position[v, 2]]; (* A247986 *)
%t Flatten[Position[v, 3]]; (* A247987 *)
%Y Cf. A247985, A247986.
%K nonn,easy
%O 1,2
%A _Clark Kimberling_, Sep 29 2014