Main diagonal of triangle A321600; a(n) = A321600(n,n-1) for n >= 1.

Terms

a(0) =2a(1) =6a(2) =26a(3) =78a(4) =242a(5) =726a(6) =2186a(7) =6558a(8) =19682a(9) =59046a(10) =177146a(11) =531438a(12) =1594322a(13) =4782966a(14) =14348906a(15) =43046718a(16) =129140162a(17) =387420486a(18) =1162261466a(19) =3486784398a(20) =10460353202a(21) =31381059606a(22) =94143178826a(23) =282429536478a(24) =847288609442