Number of permutations of (the positive integers <= n and coprime to n), where each element of the permutations is coprime to its adjacent elements.

A109813

Number of permutations of (the positive integers <= n and coprime to n), where each element of the permutations is coprime to its adjacent elements.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =2a(4) =12a(5) =2a(6) =72a(7) =24a(8) =144a(9) =12a(10) =22032a(11) =24a(12) =476928a(13) =480a(14) =1728a(15) =9600a(16) =805146624a(17) =720a(18) =36481536000a(19) =30240a(20) =1728000a(21) =312000a(23) =40320a(25) =46293120a(26) =249684249600a(27) =58423680

External references