OFFSET
1,1
COMMENTS
It appears that a(n) * b(n) either equals 2*n+1 or 1 where b is the companion sequence A214228.
EXAMPLE
a(7) = 3 which is a factor of 2*7 + 1.
MAPLE
A214229 := proc(n)
local i, r ;
i := 1;
while A143608(i) mod (2*n+1) <> 0 do
i := i+1 ;
end do;
r := 1+(A143608(i+1) mod (2*n+1)) ;
gcd(r, 2*n+1) ;
end proc: # R. J. Mathar, Jul 22 2012
MATHEMATICA
gcdN2[x_, y_] = GCD[y - x + 1, y];
r0 = 3;
table=Reap[While[r0 < 200, s1=1; s0=0; count=1; While[True, count++; temp=Mod[4*s1 - s0, r0];
If[temp==0, Break[]]; count++; s0 = s1; s1 = temp;
temp=Mod[2*s1-s0, r0]; If[temp == 0, Break[]]; s0 = s1; s1 = temp; ];
Sow[gcdN2[s1, r0], d];
r0+=2; ]][[2]];
table
CROSSREFS
KEYWORD
nonn
AUTHOR
Kenneth J Ramsey, Jul 07 2012
STATUS
approved