

A137990


Least prime p of the form c*3^n+1 with c not divisible by 3.


1



2, 7, 19, 109, 163, 487, 1459, 17497, 52489, 39367, 472393, 4960117, 5314411, 102036673, 19131877, 57395629, 86093443, 258280327, 3874204891, 23245229341, 90656394427, 585779779369, 251048476873, 9790890598009, 4518872583697
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,1


COMMENTS

a(n) is also the least prime such that 3^(n+1), but not 3^(n+2), divides 2^(a(n)1)1.


LINKS



EXAMPLE

a(8)=52489 because 52489=8*3^8+1 is prime and no smaller prime p has p1 divisible by 3^8 but not 3^9.


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



STATUS

approved



