A247986 Numbers k such that A247985(k+1) - A247985(k) = 2.

2, 5, 9, 13, 16, 20, 23, 27, 30, 34, 37, 41, 44, 48, 52, 55, 59, 62, 66, 69, 73, 76, 80, 84, 87, 91, 94, 98, 101, 105, 108, 112, 115, 119, 123, 126, 130, 133, 137, 140, 144, 147, 151, 155, 158, 162, 165, 169, 172, 176, 179, 183, 186, 190, 194, 197, 201, 204

Offset: 1

Author

Clark Kimberling, Sep 29 2014

Keywords

• nonn
• easy

Comments

Complement of A247987.

Links

• Clark Kimberling, Table of n, a(n) for n = 1..400

Crossrefs

Cf. A247985, A247987.

Programs

Mathematica

z = 100; p[k_] := p[k] = Product[(k^2 + h)/(k^2 - h), {h, 1, k}] (* Finch p. 14 *)
N[Table[p[n] - E, {n, 2, z}]]
f[n_] := f[n] = Select[1 + Range[z], p[#] - E < 1/n &, 1];
u = Flatten[Table[f[n], {n, 1, z}]] ;  (* A247985 *)
v = Differences[u];
Flatten[Position[v, 2]]; (* A247986 *)
Flatten[Position[v, 3]]; (* A247987 *)