A298867 Positions of numbers 4*p when all primes p and products 4*p are arranged in increasing order.

5, 7, 11, 13, 19, 21, 26, 29, 33, 40, 41, 46, 51, 53, 57, 63, 68, 71, 75, 81, 82, 87, 90, 95, 101, 105, 107, 110, 113, 117, 127, 131, 134, 135, 143, 146, 151, 156, 160, 165, 168, 170, 178, 180, 183, 184, 193, 202, 204, 206, 209, 214, 215, 222, 227, 233, 237

Offset

1,1

Links

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

Example

The joint ranking begins with 2,3,5,7,8,11,12,13,17,19,20, as in A298865, so that ranks occupied by products 4*p are 5,7,11,...

Mathematica

z = 200; u = Prime[Range[z]]; w = Take[Union[u, 4 u], z];  (* A298865 *)
p[n_] := If[MemberQ[u, w[[n]]], 0, 1];
t = Table[p[n], {n, 1, z}];
Flatten[Position[t, 0]]  (* A298866 *)
Flatten[Position[t, 1]]  (* A298867 *)

Crossrefs

Cf. A000040, A298866, A298866 (complement).

Sequence in context: A314297 A108409 A291345 * A039681 A375170 A216746

Adjacent sequences: A298864 A298865 A298866 * A298868 A298869 A298870

Keyword

nonn,easy

Author

Clark Kimberling, Apr 14 2018

Status

approved