1,4

Table of n, a(n) for n=1..77.

See program.

Phi of 25th composite number = 10th composite number: n=25: A002808(25)=38, phi(38) = 18 = A002808(10) so a(25)=10.

c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x]; G[x_] := x-PrimePi[x]-1; a(n)=G[EulerPhi[c[n]]]

Cf. A000010, A002808, A062298.

Sequence in context: A160325 A054989 A051631 * A055223 A174807 A181572

Adjacent sequences: A073722 A073723 A073724 * A073726 A073727 A073728

nonn

Labos Elemer, Aug 05 2002

approved