Number of zig-zag paths from top to bottom of a rectangle of width 10 with n rows.

Terms

a(0) =10a(1) =18a(2) =34a(3) =64a(4) =122a(5) =232a(6) =444a(7) =848a(8) =1626a(9) =3112a(10) =5972a(11) =11442a(12) =21964a(13) =42106a(14) =80832a(15) =155010a(16) =297570a(17) =570760a(18) =1095620a(19) =2101752a(20) =4034252a(21) =7739690a(22) =14855342a(23) =28501710a(24) =54703004a(25) =104959000a(26) =201439550a(27) =386516750a(28) =741790648a(29) =1423365002