A lower diagonal of pendular trinomial triangle A119369.

Terms

a(0) =1a(1) =3a(2) =10a(3) =36a(4) =133a(5) =501a(6) =1918a(7) =7440a(8) =29180a(9) =115522a(10) =461044a(11) =1852938a(12) =7492846a(13) =30464306a(14) =124461782a(15) =510696350a(16) =2103708187a(17) =8696498477a(18) =36066269640a(19) =150015248758a(20) =625664295594