Generalized NSW numbers.

Terms

a(0) =1a(1) =10a(2) =76a(3) =568a(4) =4240a(5) =31648a(6) =236224a(7) =1763200a(8) =13160704a(9) =98232832a(10) =733219840a(11) =5472827392a(12) =40849739776a(13) =304906608640