Number of ternary strings of length n with maximal run length two containing 112.

Terms

a(0) =1a(1) =5a(2) =20a(3) =71a(4) =237a(5) =761a(6) =2377a(7) =7278a(8) =21945a(9) =65375a(10) =192861a(11) =564387a(12) =1640496a(13) =4741103a(14) =13634501a(15) =39042437a(16) =111379025a(17) =316687006a(18) =897796581a(19) =2538530615a(20) =7160768785a(21) =20156241155a(22) =56626360256a(23) =158804376883a(24) =444638710925