Number of length n+6 0..2 arrays with at most one downstep in every n consecutive neighbor pairs.

Terms

a(0) =2187a(1) =5157a(2) =7498a(3) =10125a(4) =14001a(5) =19263a(6) =25578a(7) =33063a(8) =41851a(9) =52092a(10) =63954a(11) =77624a(12) =93309a(13) =111237a(14) =131658a(15) =154845a(16) =181095a(17) =210730a(18) =244098a(19) =281574a(20) =323561a(21) =370491a(22) =422826a(23) =481059a(24) =545715a(25) =617352a(26) =696562a(27) =783972a(28) =880245a(29) =986081