Number of base 13 n-digit numbers with adjacent digits differing by one or less.

Terms

a(0) =1a(1) =13a(2) =37a(3) =107a(4) =311a(5) =907a(6) =2651a(7) =7761a(8) =22749a(9) =66747a(10) =195995a(11) =575893a(12) =1693073a(13) =4979777a(14) =14652601a(15) =43128637a(16) =126982109a(17) =373962395a(18) =1101557803a(19) =3245398895a(20) =9563118423a(21) =28183332105a(22) =83068897785a(23) =244867352543a(24) =721877651203