Number of strings of length n composed of symbols from the circular list [1,2,3,4] such that adjacent symbols in the string must be adjacent in the list. No runs of length 2 or more are allowed for symbols 1 and 3.
A277236
Number of strings of length n composed of symbols from the circular list [1,2,3,4] such that adjacent symbols in the string must be adjacent in the list. No runs of length 2 or more are allowed for symbols 1 and 3.
Terms
- a(0) =1a(1) =4a(2) =10a(3) =26a(4) =66a(5) =170a(6) =434a(7) =1114a(8) =2850a(9) =7306a(10) =18706a(11) =47930a(12) =122754a(13) =314474a(14) =805490a(15) =2063386a(16) =5285346a(17) =13538890a(18) =34680274a(19) =88835834a(20) =227556930a(21) =582900266a(22) =1493127986a(23) =3824729050a(24) =9797240994a(25) =25096157194a(26) =64285121170a(27) =164669749946a(28) =421810234626
External references
- oeis: A277236