OFFSET
0,3
COMMENTS
a(n) is even for all n >= 2.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
MAPLE
a[0]:=1: a[1]:=1: for n from 2 to 130 do a[n]:=igcd(a[n-1], n)+igcd(a[n-2], n) od: seq(a[n], n=0..130); # Emeric Deutsch, Apr 16 2007
MATHEMATICA
nxt[{n_, a_, b_}]:={n+1, b, GCD[b, n+1]+GCD[a, n+1]}; Join[{1}, NestList[nxt, {1, 1, 1}, 110][[All, 3]]] (* Harvey P. Dale, May 23 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 29 2007
EXTENSIONS
More terms from Emeric Deutsch, Apr 16 2007
Incorrect g.f. removed by Georg Fischer, May 15 2019
STATUS
approved