OFFSET
1,1
COMMENTS
The numbers 1, 2, 4, 7, 9, 11, 32, 322, 498, 685, 880, ... are not in the sequence.
LINKS
Robert Israel, Table of n, a(n) for n = 1..2000
EXAMPLE
3+1 = 4, 3*5+1 = 16, 3*5*6+1 = 91, 3*5*6*8+1 = 721, etc. are nonprimes.
MAPLE
A[1]:= 3: P:= 3:
for n from 2 to 100 do
for k from A[n-1]+1 do
if not isprime(P*k+1) then
A[n]:= k; P:= P*k; break
fi
od od:
seq(A[i], i=1..100); # Robert Israel, Jun 18 2019
MATHEMATICA
seq={3}; Do[n=Last[seq]+1; While[PrimeQ[n Times@@seq+1], n++]; AppendTo[seq, n]; , {100}]; seq
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Dec 15 2013
STATUS
approved