Number of permutations of 1..n arranged in a circle with exactly 3 adjacent element pairs in decreasing order.

A151576

Number of permutations of 1..n arranged in a circle with exactly 3 adjacent element pairs in decreasing order.

Terms

    a(0) =0a(1) =4a(2) =55a(3) =396a(4) =2114a(5) =9528a(6) =38637a(7) =146080a(8) =526240a(9) =1831644a(10) =6217523a(11) =20716164a(12) =68059710a(13) =221195824a(14) =712856665a(15) =2282058360a(16) =7266358556a(17) =23035517940a(18) =72760054815a(19) =229112753980a(20) =719545590010

External references