a(n) = C(n+1) - C(n-1) - 2*C(n-2) where C(n) = A000108(n) are the Catalan numbers.

A382668

a(n) = C(n+1) - C(n-1) - 2*C(n-2) where C(n) = A000108(n) are the Catalan numbers.

Terms

    a(0) =2a(1) =10a(2) =33a(3) =108a(4) =359a(5) =1214a(6) =4169a(7) =14508a(8) =51064a(9) =181492a(10) =650522a(11) =2348856a(12) =8535921a(13) =31197430a(14) =114601065a(15) =422891340a(16) =1566903060a(17) =5827192140a(18) =21743726430a(19) =81383916840a(20) =305465105790

External references