A390790 - OEIS

%I #5 Dec 01 2025 21:07:18

%S 1,5,8,11,14,18,20,23,26,29,33,35,39,41,44,47,48,50,53,56,61,62,63,65,

%T 68,73,74,78,81,83,86,89,94,95,98,103,104,105,109,110,111,113,116,119,

%U 124,125,128,131,134,138,140,145,146,151,152,153,155,158,163

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

%t z = 1500; f[x_] := f[x] = 2*x;

%t u[n_] := NextPrime[f[n], -1]; v[n_] := NextPrime[f[n]];

%t Select[Range[z], f[#] - v[#] < u[#] - f[#] &]   (* A390788 *)

%t Select[Range[z], f[#] - v[#] == u[#] - f[#] &]  (* A390789 *)

%t Select[Range[z], f[#] - v[#] > u[#] - f[#] &]   (* A390790 *)

%Y Cf. A000027, A000040, A390788, A390789.

%K nonn

%O 1,2

%A _Clark Kimberling_, Nov 25 2025