a(n) = Sum_{k=1..n+1} |A341287(n,k)|.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =19a(5) =69a(6) =249a(7) =1025a(8) =4833a(9) =21481a(10) =126517a(11) =615669a(12) =4161321a(13) =22894537a(14) =163938841a(15) =1016069027a(16) =8491341479a(17) =58444280449a(18) =508568676159