OFFSET
1,1
COMMENTS
2p and prime powers are here.
PROG
(PARI) isok(n) = {my(va = select(x->(gcd(n, x)==1), [1..n])); vd = vector(#va-1, k, va[k+1] - va[k]); #Set(vd) == 2; } \\ Michel Marcus, Mar 30 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 09 2002
STATUS
approved