Number of ways to arrange the numbers 1..n in a circle (up to direction) such that every two adjacent numbers are relatively prime.

A086595

Number of ways to arrange the numbers 1..n in a circle (up to direction) such that every two adjacent numbers are relatively prime.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =2a(4) =12a(5) =4a(6) =72a(7) =72a(8) =720a(9) =576a(10) =22032a(11) =7776a(12) =476928a(13) =400896a(14) =6352992a(15) =8515584a(16) =805146624a(17) =279023616a(18) =36481536000a(19) =23627980800a(20) =881012367360

External references