Number of strings of length n over a 5-letter alphabet that begin with a nontrivial palindrome.
A249638
Number of strings of length n over a 5-letter alphabet that begin with a nontrivial palindrome.
Terms
- a(0) =0a(1) =0a(2) =5a(3) =45a(4) =245a(5) =1305a(6) =6605a(7) =33405a(8) =167405a(9) =838845a(10) =4196045a(11) =20989245a(12) =104955245a(13) =524820945a(14) =2624149445a(15) =13120970445a(16) =65605075445a(17) =328026491505
External references
- oeis: A249638