1,2

These would be the units if the structure formed a ring (which it does not).

Table of n, a(n) for n=1..61.

22 is a member since 22*88 = 1. So is 23 since 23*8 = 1. 10 is not a member, even though 10 divides 9, since 10*9 = 0.

Sequence in context: A180484 A007602 A167620 * A193498 A239087 A095227

Adjacent sequences: A169932 A169933 A169934 * A169936 A169937 A169938

nonn,base

David Applegate, Marc LeBrun and N. J. A. Sloane, Jul 21 2010

approved