a(n) is the number of integer strings s(0),...,s(n) counted by array T in A026374 that have s(n)=2; also a(n) = T(2n,n-1).

A026376

a(n) is the number of integer strings s(0),...,s(n) counted by array T in A026374 that have s(n)=2; also a(n) = T(2n,n-1).

Terms

    a(0) =1a(1) =6a(2) =30a(3) =144a(4) =685a(5) =3258a(6) =15533a(7) =74280a(8) =356283a(9) =1713690a(10) =8263596a(11) =39938616a(12) =193419915a(13) =938430990a(14) =4560542550a(15) =22195961280a(16) =108171753355a(17) =527816696850

External references