Main diagonal of triangle A131823: a(n) = A131823(n,n) for n>=0.

Terms

a(0) =1a(1) =1a(2) =2a(3) =7a(4) =24a(5) =86a(6) =316a(7) =1177a(8) =4424a(9) =16744a(10) =63724a(11) =243618a(12) =934870a(13) =3598960a(14) =13892776a(15) =53756263a(16) =208434024a(17) =809658440a(18) =3150218032a(19) =12274694280a(20) =47890456576a(21) =187068828772a(22) =731511810152