A247987 Numbers k such that A247985(k+1) - A247985(k) = 3.

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, 36, 38, 39, 40, 42, 43, 45, 46, 47, 49, 50, 51, 53, 54, 56, 57, 58, 60, 61, 63, 64, 65, 67, 68, 70, 71, 72, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 88, 89, 90, 92

Offset: 1

Author

Clark Kimberling, Sep 29 2014

Keywords

• nonn
• easy

Comments

Complement of A247986.

Links

• Clark Kimberling, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A247985, A247986.

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 *)