q-Pell numbers with q=2.

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =20a(5) =88a(6) =496a(7) =3808a(8) =39360a(9) =566144a(10) =11208448a(11) =312282624a(12) =12102016000a(13) =663758845952