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

1, 3, 12, 42, 165, 3000, 2142, 39270, 838695, 2185092, 194467182, 649154415, 33547795512, 40753286805, 24563658547425, 1364238471026340, 2297427262231332, 1662166966658270160, 783186317937632697, 404695317060455732220, 162293533192142440777455, 634357227813958501290435

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Formula

a(n) = 0 (mod 3) for n >= 2.

a(n) = 0 or 12 (mod 15) for n >= 3.

Maple

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:

Prog

(PARI) A190911(n)=n*=n+3; forprime(p=3, , if(n%p, return(p)))
{my(v=[0], t=3, p=5);
print1("1, 3");
forprime(q=7, 1000,
    u=vector(#v);
    for(i=1, #u,
        u[i]=lift(chinese(Mod(v[i], t), Mod( 0, p)));
        v[i]=lift(chinese(Mod(v[i], t), Mod(-3, p)))
    );
    v=vecsort(concat(u, v));
    for(j=2, #v,
        if(A190911(v[j])==q,
            print1(", "v[j]);
            break
        )
    );
    t*=p;
    p=q
)} \\ Charles R Greathouse IV, Oct 09 2011

Crossrefs

Cf. A190911.

Sequence in context: A094970 A065179 A048121 * A066987 A366617 A290918

Adjacent sequences: A191109 A191110 A191111 * A191113 A191114 A191115

Keyword

nonn

Author

Nathaniel Johnston, May 26 2011

Extensions

a(11)-a(22) from Charles R Greathouse IV, Oct 09 2011

Status

approved