OFFSET
0,5
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
MATHEMATICA
a[0]:= 1; a[n_]:= a[n] =Sum[If[GCD[k, n]!=1, a[k], 0], {k, 0, n-1}];
Table[a[n], {n, 0, 50}] (* G. C. Greubel, Jul 31 2019 *)
PROG
(PARI) a(n) = if(n==0, 1, sum(j=0, n-1, if(gcd(j, n)!=1, a(j), 0)));
vector(50, n, n--; a(n)) \\ G. C. Greubel, Jul 31 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved