cp's OEIS Frontend

A317964 Prime numbers in the lexicographically earliest sequence of positive integers whose prime indices are not already in the sequence (A304360).

%I A317964 #12 Mar 19 2019 23:00:27
%S A317964 2,5,13,17,23,31,37,43,47,61,67,73,79,89,103,107,109,113,137,149,151,
%T A317964 163,167,179,181,193,197,223,227,233,241,251,257,263,269,271,277,281,
%U A317964 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
%N A317964 Prime numbers in the lexicographically earliest sequence of positive integers whose prime indices are not already in the sequence (A304360).
%C A317964 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
%H A317964 Robert Israel, <a href="/A317964/b317964.txt">Table of n, a(n) for n = 1..10000</a>
%p A317964 count:= 0:
%p A317964 P:= {}: A:= NULL:
%p A317964 for n from 2 while count < 100 do
%p A317964   pn:= numtheory:-factorset(n);
%p A317964   if pn intersect P = {} then
%p A317964     P:= P union {ithprime(n)};
%p A317964     if isprime(n) then A:= A, n; count:= count+1 fi;
%p A317964   fi
%p A317964 od:
%p A317964 A; # _Robert Israel_, Aug 26 2018
%t A317964 aQ[n_]:=n==1||Or@@Cases[FactorInteger[n],{p_,_}:>!aQ[PrimePi[p]]];
%t A317964 Prime[Select[Range[100],aQ]] (* _Gus Wiseman_, Mar 19 2019 *)
%Y A317964 Cf. A000720, A001462, A007097, A060197, A079254, A112798, A276625, A277098, A290822, A304360, A306844.
%Y A317964 Cf. A324695, A324698, A324704, A324741, A324756, A324758, A324765, A324766, A324768.
%K A317964 nonn
%O A317964 1,1
%A A317964 _N. J. A. Sloane_, Aug 26 2018