1,3

a(a(n)) = a(n).

Table of n, a(n) for n=1..81.

Multiplicative with a(p) = (if p+2 or p-2 is prime then p else 1), p prime.

a(92) = a(2*2*23) = 1; a(93) = a(3*31) = 3*31 = 93.

Cf. A007510, A000040.

Sequence in context: A145799 A244568 A098985 * A161955 A276234 A000265

Adjacent sequences: A072960 A072961 A072962 * A072964 A072965 A072966

nonn,mult

Reinhard Zumkeller, Aug 20 2002

approved