a(4)=a(8)=a(16)=0 because when n>2 is a power of a prime p, the (n-1)-st difference of any permutation of 1..n is a multiple of p.
Table of n, a(n) for n=2..16.
Cf. A174103, A130803
Sequence in context: A182062 A219859 A168615 * A135006 A086118 A104986
Adjacent sequences: A174101 A174102 A174103 * A174105 A174106 A174107
R. H. Hardin Mar 07 2010, comment from Maximilian Hasler and Max Alekseyev, on the Sequence Fans Mailing List