OFFSET
1,3
EXAMPLE
a(4)*a(5) = 40. So a(6) = the sixth integer from among those positive integers coprime to 40 (i.e., the sixth integer in the sequence 1,3,7,9,11,13,17,19,21,23,...). So a(6) = 13.
MAPLE
a[1]:=1: a[2]:=1: for n from 3 to 80 do A:={}: for i from 1 to 500 do if gcd(i, a[n-1]*a[n-2])=1 then A:=A union {i} else fi od: a[n]:=A[n]: od: seq(a[n], n=1..80); # Emeric Deutsch, Apr 12 2007
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 30 2007
EXTENSIONS
More terms from Emeric Deutsch, Apr 12 2007
STATUS
approved