Number of permutations of 2..n+1 with no element greater than or equal to the sum of its neighbors.
A180890
Number of permutations of 2..n+1 with no element greater than or equal to the sum of its neighbors.
Terms
- a(0) =1a(1) =0a(2) =2a(3) =6a(4) =20a(5) =90a(6) =550a(7) =3512a(8) =25378a(9) =200558a(10) =1778156a(11) =17016488a(12) =177741892a(13) =1984308356a(14) =23873823014a(15) =304944376412
External references
- oeis: A180890