T(2n+1,n+1), T given by A026769.

Terms

a(0) =1a(1) =3a(2) =11a(3) =44a(4) =186a(5) =819a(6) =3725a(7) =17402a(8) =83156a(9) =405116a(10) =2006696a(11) =10083578a(12) =51303146a(13) =263851841a(14) =1369807435a(15) =7170160392a(16) =37803475750a(17) =200584271466