Sequence of the next-to-last entries in the rows of A099961.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =10a(5) =23a(6) =64a(7) =179a(8) =514a(9) =1685a(10) =5940a(11) =20676a(12) =79319a(13) =334819a(14) =1373858a(15) =6075215a(16) =29763791a(17) =140830911a(18) =707344776a(19) =3937348498a(20) =21115879847a(21) =118932148555a(22) =740523625011