Number of (s,3) gates.

Terms

a(0) =3a(1) =18a(2) =87a(3) =396a(4) =1677a(5) =6877a(6) =27285a(7) =105818a(8) =401467a(9) =1495034a(10) =5472180a(11) =19725210a(12) =70108822a(13) =246015436a(14) =853123327a(15) =2926232947a(16) =9935253065a(17) =33412999042a(18) =111371708179a(19) =368118865729