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A191112 First occurrence of the n-th odd prime in A190911.

%I A191112 #13 Sep 26 2015 18:40:45
%S A191112 1,3,12,42,165,3000,2142,39270,838695,2185092,194467182,649154415,
%T A191112 33547795512,40753286805,24563658547425,1364238471026340,
%U A191112 2297427262231332,1662166966658270160,783186317937632697,404695317060455732220,162293533192142440777455,634357227813958501290435
%N A191112 First occurrence of the n-th odd prime in A190911.
%F A191112 a(n) = 0 (mod 3) for n >= 2.
%F A191112 a(n) = 0 or 12 (mod 15) for n >= 3.
%p A191112 A190911 := proc(n) option remember: local k: for k from 3 by 2 do if(gcd(k,n)=1 and gcd(k,n+3)=1)then return k: fi: od: end: for n from 2 do p:=ithprime(n): for k from 1 do if(A190911(k)=p)then print(k): break: fi: od: od:
%o A191112 (PARI) A190911(n)=n*=n+3;forprime(p=3,,if(n%p,return(p)))
%o A191112 {my(v=[0],t=3,p=5);
%o A191112 print1("1, 3");
%o A191112 forprime(q=7,1000,
%o A191112     u=vector(#v);
%o A191112     for(i=1,#u,
%o A191112         u[i]=lift(chinese(Mod(v[i],t),Mod( 0,p)));
%o A191112         v[i]=lift(chinese(Mod(v[i],t),Mod(-3,p)))
%o A191112     );
%o A191112     v=vecsort(concat(u,v));
%o A191112     for(j=2,#v,
%o A191112         if(A190911(v[j])==q,
%o A191112             print1(", "v[j]);
%o A191112             break
%o A191112         )
%o A191112     );
%o A191112     t*=p;
%o A191112     p=q
%o A191112 )} \\ _Charles R Greathouse IV_, Oct 09 2011
%Y A191112 Cf. A190911.
%K A191112 nonn
%O A191112 1,2
%A A191112 _Nathaniel Johnston_, May 26 2011
%E A191112 a(11)-a(22) from _Charles R Greathouse IV_, Oct 09 2011