Sums of antidiagonals of A099239.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =22a(5) =57a(6) =155a(7) =441a(8) =1311a(9) =4066a(10) =13130a(11) =44046a(12) =153144a(13) =550706a(14) =2044248a(15) =7819897a(16) =30779570a(17) =124487688a(18) =516723174a(19) =2198726181a(20) =9581247648a(21) =42717268934a(22) =194688593966a(23) =906331074605