a(n) = a(n-2) + (2n-1)a(n-1); a(0)=1, a(1)=1.

A025164

a(n) = a(n-2) + (2n-1)a(n-1); a(0)=1, a(1)=1.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =21a(4) =151a(5) =1380a(6) =15331a(7) =200683a(8) =3025576a(9) =51635475a(10) =984099601a(11) =20717727096a(12) =477491822809

External references