OFFSET
1,1
COMMENTS
This sequence would have terminated after only one term if a(1) equaled 2 or 3.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(5) = 37. So we want to look at the primes > 37 to get a(6). 41 - 1 is divisible by a(1)=5. (And 41+1 is divisible by a(2)=7.) 43-1 is divisible by a(2)=7. 47-1 is divisible by a(4)=23. By 53-1 is not divisible by any earlier terms of the sequence, and 53+1 is not divisible by any earlier terms of the sequence. So a(6) = 53.
MAPLE
Res:= 5: S:= 5: p:= 5:
count:= 1:
while count < 100 do
p:= nextprime(p);
if igcd((p+1)*(p-1), S) = 1 then
count:= count+1; Res:= Res, p;
S:= S*p;
fi
od:
Res; # Robert Israel, Jun 16 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Oct 06 2009
EXTENSIONS
Extended by Ray Chandler, Mar 12 2010
STATUS
approved