Sequence of the next-to-last entries in the rows of A099964.

Terms

a(0) =1a(1) =1a(2) =3a(3) =6a(4) =14a(5) =39a(6) =109a(7) =313a(8) =900a(9) =2943a(10) =10403a(11) =36195a(12) =127474a(13) =447352a(14) =1711141a(15) =7234223a(16) =29672119a(17) =123515469a(18) =511672779a(19) =2123410053a(20) =9349845765a(21) =45883313142a(22) =216991244323