OFFSET
1,6
COMMENTS
Does every integer appear?
EXAMPLE
a(10) is the number of numbers between 1 and 9 that are coprime to 10*11*12, which leaves 1 and 7, hence a(10) = 2.
MATHEMATICA
Table[Count[Range[1, n-1], _?(CoprimeQ[#, (n(n+1)(n+2))]&)], {n, 80}] (* Harvey P. Dale, May 07 2016 *)
PROG
(PARI) newphi(v)=local(vl, fl, np); vl=length(v); np=0; for (s=1, v[1], fl=false; for (r=1, vl, if (gcd(s, v[r])>1, fl=true; break)); if (fl==false, np++)); np v=vector(3); for (i=1, 50, v[1]=i; v[2]=i+1; v[3]=i+2; print1(newphi(v)", "))
(PARI) a(n) = sum(i=1, n-1, gcd(i, n*(n+1)*(n+2)) == 1); \\ Michel Marcus, Mar 17 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Jon Perry, Dec 12 2002
EXTENSIONS
More terms from Michel Marcus, Mar 17 2014
STATUS
approved