OFFSET
1,5
PROG
(PARI) a061498(n) = {my(va = select(x->(gcd(n, x)==1), [1..n])); vd = vector(#va-1, k, va[k+1] - va[k]); #Set(vd); }
a(n) = eulerphi(n) - a061498(n); \\ Michel Marcus, Jul 08 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 09 2002
STATUS
approved