A247986 - OEIS

%I #4 Sep 30 2014 15:57:04

%S 2,5,9,13,16,20,23,27,30,34,37,41,44,48,52,55,59,62,66,69,73,76,80,84,

%T 87,91,94,98,101,105,108,112,115,119,123,126,130,133,137,140,144,147,

%U 151,155,158,162,165,169,172,176,179,183,186,190,194,197,201,204

%N Numbers k such that A247985(k+1) - A247985(k) = 2.

%C Complement of A247987.

%H Clark Kimberling, <a href="/A247986/b247986.txt">Table of n, a(n) for n = 1..400</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, A247987.

%K nonn,easy

%O 1,1

%A _Clark Kimberling_, Sep 29 2014