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A298861 Rank of n-th prime when all the primes and twice-primes are jointly ranked. 2
1, 2, 4, 6, 8, 9, 11, 12, 14, 16, 17, 19, 21, 22, 24, 25, 27, 28, 30, 31, 32, 34, 36, 38, 40, 41, 42, 44, 45, 46, 49, 50, 52, 53, 56, 57, 58, 60, 62, 63, 65, 66, 67, 68, 70, 71, 74, 77, 79, 80, 81, 82, 83, 84, 86, 88, 89, 90, 92, 94, 95, 96, 99, 100, 101 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

EXAMPLE

A001751 = ordered sequence of primes and twice-primes: 2,3,4,5,6,7,10,... in which the primes occupy ranks 1,2,4,6,...

MATHEMATICA

z = 1000; u = Prime[Range[z]]; w = Take[Union[u, 2 u], z];

p[n_] := If[MemberQ[u, w[[n]]], 0, 1];

Take[w, z];  (* A001751 *)

t = Table[p[n], {n, 1, z}];

Flatten[Position[t, 0]];  (* A298861 *)

Flatten[Position[t, 1]];  (* A298862 *)

CROSSREFS

Cf. A000040, A001751, A298862 (complement).

Sequence in context: A184012 A186354 A186149 * A114571 A050091 A184740

Adjacent sequences:  A298858 A298859 A298860 * A298862 A298863 A298864

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Feb 13 2018

STATUS

approved

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Last modified January 16 05:22 EST 2022. Contains 350374 sequences. (Running on oeis4.)