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A191112
First occurrence of the n-th odd prime in A190911.
1
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
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 A375203
KEYWORD
nonn
AUTHOR
Nathaniel Johnston, May 26 2011
EXTENSIONS
a(11)-a(22) from Charles R Greathouse IV, Oct 09 2011
STATUS
approved