0,2

with(numtheory): phi(7^n-1)/n;

Sequence in context: A076122 A123290 A088675 this_sequence A152124 A147722 A089387

Adjacent sequences: A027740 A027741 A027742 this_sequence A027744 A027745 A027746

nonn

N. J. A. Sloane (njas(AT)research.att.com).