login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A317964 Prime numbers in the lexicographically earliest sequence of positive integers whose prime indices are not already in the sequence (A304360). 2
2, 5, 13, 17, 23, 31, 37, 43, 47, 61, 67, 73, 79, 89, 103, 107, 109, 113, 137, 149, 151, 163, 167, 179, 181, 193, 197, 223, 227, 233, 241, 251, 257, 263, 269, 271, 277, 281, 307, 317, 347, 349, 353, 359, 379, 383, 389, 397, 419, 421, 431, 433, 449, 457, 463, 467, 487, 499, 503, 509, 521, 523, 547 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also primes whose prime index is not in A304360, or is in A324696. A prime index of n is a number m such that prime(m) divides n. - Gus Wiseman, Mar 19 2019

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

count:= 0:

P:= {}: A:= NULL:

for n from 2 while count < 100 do

  pn:= numtheory:-factorset(n);

  if pn intersect P = {} then

    P:= P union {ithprime(n)};

    if isprime(n) then A:= A, n; count:= count+1 fi;

  fi

od:

A; # Robert Israel, Aug 26 2018

MATHEMATICA

aQ[n_]:=n==1||Or@@Cases[FactorInteger[n], {p_, _}:>!aQ[PrimePi[p]]];

Prime[Select[Range[100], aQ]] (* Gus Wiseman, Mar 19 2019 *)

CROSSREFS

Cf. A000720, A001462, A007097, A060197, A079254, A112798, A276625, A277098, A290822, A304360, A306844.

Cf. A324695, A324698, A324704, A324741, A324756, A324758, A324765, A324766, A324768.

Sequence in context: A215424 A215428 A019362 * A075451 A109515 A135933

Adjacent sequences:  A317961 A317962 A317963 * A317965 A317966 A317967

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Aug 26 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 19 19:19 EDT 2021. Contains 347564 sequences. (Running on oeis4.)