OFFSET
0,3
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
MAPLE
f:=proc(n) option remember;
if n <= 1 then 1
elif gcd(n, f(n-1))>1 then f(n-1)/gcd(n, f(n-1))
else 3*f(n-1); fi; end;
[seq(f(n), n=0..50)];
# N. J. A. Sloane, Feb 14 2015
MATHEMATICA
nxt[{n_, a_}]:={n+1, If[CoprimeQ[a, n+1], 3a, a/GCD[a, n+1]]}; Join[{1}, Transpose[ NestList[nxt, {1, 1}, 50]][[2]]] (* Harvey P. Dale, Feb 14 2015 *)
PROG
(PARI) A=vector(1000, i, 1); for(n=2, #A, A[n]=if(gcd(A[n-1], n)>1, A[n-1]/gcd(A[n-1], n), A[n-1]*3)) \\ M. F. Hasler, Feb 15 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Ctibor O. Zizka, Dec 26 2007
EXTENSIONS
Offset, definition, and terms corrected by N. J. A. Sloane, Feb 14 2015
STATUS
approved