A390790 Numbers k such that 2*k - (greatest prime < 2*k) > (least prime > 2*k) - 2*k.

1, 5, 8, 11, 14, 18, 20, 23, 26, 29, 33, 35, 39, 41, 44, 47, 48, 50, 53, 56, 61, 62, 63, 65, 68, 73, 74, 78, 81, 83, 86, 89, 94, 95, 98, 103, 104, 105, 109, 110, 111, 113, 116, 119, 124, 125, 128, 131, 134, 138, 140, 145, 146, 151, 152, 153, 155, 158, 163

Offset

1,2

Links

Table of n, a(n) for n=1..59.

Mathematica

z = 1500; f[x_] := f[x] = 2*x;
u[n_] := NextPrime[f[n], -1]; v[n_] := NextPrime[f[n]];
Select[Range[z], f[#] - v[#] < u[#] - f[#] &]   (* A390788 *)
Select[Range[z], f[#] - v[#] == u[#] - f[#] &]  (* A390789 *)
Select[Range[z], f[#] - v[#] > u[#] - f[#] &]   (* A390790 *)

Crossrefs

Cf. A000027, A000040, A390788, A390789.

Sequence in context: A314388 A022798 A022808 * A104279 A184919 A063247

Adjacent sequences: A390787 A390788 A390789 * A390791 A390792 A390793

Keyword

nonn

Author

Clark Kimberling, Nov 25 2025

Status

approved