1,2

For n = odd integer the middle term of all counted permutations must be 1.

For n = 6, the permutation (3,2,1,6,4,5) is not counted because p(2)=2 is not coprime to p(5)=4. However, the permutation (3,6,1,4,5,2) is counted because GCD(3,2) = GCD(6,5) = GCD(1,4) = 1.

Sequence in context: A112327 A093114 A016740 this_sequence A088139 A113123 A076615

Adjacent sequences: A133919 A133920 A133921 this_sequence A133923 A133924 A133925

more,nonn

Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Jan 07 2008