A298863 Ranks of primes p when all primes p and products 3*p are jointly ranked.

1, 2, 3, 5, 7, 8, 10, 11, 13, 14, 15, 17, 19, 20, 21, 23, 25, 26, 27, 29, 30, 31, 32, 34, 36, 37, 38, 39, 40, 42, 44, 46, 47, 48, 50, 51, 52, 54, 55, 56, 58, 59, 61, 62, 63, 64, 66, 69, 70, 71, 72, 74, 75, 77, 78, 79, 81, 82, 83, 84, 85, 87, 89, 91, 92, 93

Offset

1,2

Links

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

Example

A105585 = ordered sequence of primes p and products 3*p:  2, 3, 5, 6, 7, 9, 11, 13, 15, 17, ... in which primes occupy ranks 1,2,3,5,7,8,10,...

Mathematica

z = 1000; u = Prime[Range[z]]; w = Take[Union[u, 3 u], z];
p[n_] := If[MemberQ[u, w[[n]]], 0, 1];
Take[w, z];  (* A105585 *)
t = Table[p[n], {n, 1, z}];
Flatten[Position[t, 0]];  (* A298863 *)
Flatten[Position[t, 1]];  (* A298864 *)

Crossrefs

Cf. A000040, A105585, A298864 (complement).

Sequence in context: A232532 A076798 A185596 * A377898 A184588 A047488

Adjacent sequences: A298860 A298861 A298862 * A298864 A298865 A298866

Keyword

nonn,easy

Author

Clark Kimberling, Feb 13 2018

Status

approved