Number of distributive lattices; also number of paths with n turns when light is reflected from 9 glass plates.

A030113

Number of distributive lattices; also number of paths with n turns when light is reflected from 9 glass plates.

Terms

    a(0) =1a(1) =9a(2) =45a(3) =285a(4) =1695a(5) =10317a(6) =62349a(7) =377739a(8) =2286648a(9) =13846117a(10) =83833256a(11) =507596153a(12) =3073376281a(13) =18608642427a(14) =112671254094a(15) =682200039446

External references