A048121 a(n) = (1/2)*T(2n,n+1), where T is given by A048113.

0, 0, 1, 3, 12, 42, 156, 570, 2124, 7926, 29844, 112812, 428712, 1635108, 6259236, 24031260, 92517180, 357019224, 1380671532, 5349496152, 20762603724, 80709201504, 314178212928, 1224576411084, 4778651920092, 18667769062044

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A048113.