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A333364 Indices of primes p whose order of primeness A078442(p) is prime. 2
2, 3, 7, 11, 13, 17, 19, 23, 29, 37, 41, 43, 47, 53, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are prime.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..10000

N. Fernandez, An order of primeness, F(p)

N. Fernandez, An order of primeness [cached copy, included with permission of the author]

FORMULA

{ p in primes : A049076(p) is prime }.

a(n) = pi(A333353(n)), with pi = A000720.

EXAMPLE

11 is a term: prime(11) = 31 -> 11 -> 5 -> 3 -> 2 -> 1, five (a prime number of) steps "->" = pi = A000720.

MAPLE

b:= proc(n) option remember;

      `if`(isprime(n), 1+b(numtheory[pi](n)), 0)

    end:

a:= proc(n) option remember; local p;

      p:= `if`(n=1, 1, a(n-1));

      do p:= nextprime(p);

         if isprime(b(p)+1) then break fi

      od; p

    end:

seq(a(n), n=1..62);

CROSSREFS

Cf. A000040, A000720, A049076, A333353.

Sequence in context: A020634 A173555 A086339 * A332787 A181173 A216277

Adjacent sequences:  A333361 A333362 A333363 * A333365 A333366 A333367

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Mar 16 2020

STATUS

approved

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Last modified May 7 01:15 EDT 2021. Contains 343635 sequences. (Running on oeis4.)