Column 0 of triangles A136220 and A136228; also equals column 0 of tables A136217 and A136218.
A136221
Column 0 of triangles A136220 and A136228; also equals column 0 of tables A136217 and A136218.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =15a(4) =108a(5) =1036a(6) =12569a(7) =185704a(8) =3247546a(9) =65762269a(10) =1515642725a(11) =39211570981
External references
- oeis: A136221