The number of words of length n with letters a, b, c with at least as many a's as b's and at least as many b's as c's and no adjacent letters forming the pattern aba or abc.
A174982
The number of words of length n with letters a, b, c with at least as many a's as b's and at least as many b's as c's and no adjacent letters forming the pattern aba or abc.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =8a(4) =15a(5) =38a(6) =120a(7) =258a(8) =683a(9) =2116a(10) =4796a(11) =12800a(12) =39094a(13) =91412a(14) =245478a(15) =742376a(16) =1772851a(17) =4779936a(18) =14342766a(19) =34772193a(20) =94010374a(21) =280321572a(22) =687416534a(23) =1862299561a(24) =5524586198a(25) =13670204608a(26) =37092812772a(27) =109567253600a(28) =273104180926a(29) =741976123650
External references
- oeis: A174982