OFFSET
1,4
LINKS
C. H. Gribble, Table of n, a(n) for n=1,...,1000.
PROG
(PARI) squares(n) = {local(s = Set()); for (j=1, n, s = setunion(s, Set(j^2 % n)); ); return (s); }
qnonr(n) = {local(s = Set()); sq = squares(n); for (j=0, n-1, if (length(setintersect(Set(j), sq))==0, s = setunion(s, Set(j))); ); return (s); }
a(n) = {s = Set(); qnr = qnonr(n); for (j=1, #qnr, if (issquarefree(eval(qnr[j])), s = setunion(s, Set(qnr[j]))); ); return (#s); } \\ Michel Marcus, Jul 23 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Christopher Hunt Gribble, Sep 30 2009
EXTENSIONS
a(1) added by Christopher Hunt Gribble, Oct 05 2009
STATUS
approved