1,3

Greatest values occur at primorial numbers (A002110).

Table of n, a(n) for n=1..105.

If n is prime, its reduced residue system consists of all numbers below n. But the difference 2 arises from d=1-(n-1)=-n+2 (mod n).

Cf. A048670. Essentially same as A048669.

Sequence in context: A211454 A242310 A102298 * A075016 A279409 A102445

Adjacent sequences: A049295 A049296 A049297 * A049299 A049300 A049301

nonn

Labos Elemer

approved