Column 2 of triangle A128562.

Terms

a(0) =1a(1) =4a(2) =12a(3) =29a(4) =61a(5) =120a(6) =222a(7) =392a(8) =669a(9) =1109a(10) =1792a(11) =2838a(12) =4413a(13) =6751a(14) =10184a(15) =15169a(16) =22332a(17) =32538a(18) =46955a(19) =67162a(20) =95288a(21) =134173a(22) =187593a(23) =260562a(24) =359682a(25) =493622a(26) =673736a(27) =914814a(28) =1236057a(29) =1662340