First differences of A323289.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =15a(6) =35a(7) =77a(8) =226a(9) =1003a(10) =4627a(11) =22195a(12) =107764a(13) =553107a(14) =3219398a(15) =20940662a(16) =146173751a(17) =1077052928