Descending dungeons: see Comments lines for definition.

Terms

a(0) =10a(1) =11a(2) =13a(3) =16a(4) =20a(5) =25a(6) =31a(7) =38a(8) =46a(9) =55a(10) =65a(11) =87a(12) =135a(13) =239a(14) =463a(15) =943a(16) =1967a(17) =4143a(18) =8751a(19) =18479a(20) =38959a(21) =103471a(22) =306223a(23) =942127a(24) =2932783a(25) =9153583a(26) =28562479a(27) =89028655a(28) =277145647a(29) =861652015