Number of quaternary words either empty or beginning with the first character of the alphabet, that can be built by inserting n doublets into the initially empty word.
A194724
Number of quaternary words either empty or beginning with the first character of the alphabet, that can be built by inserting n doublets into the initially empty word.
Terms
- a(0) =1a(1) =1a(2) =7a(3) =58a(4) =523a(5) =4966a(6) =48838a(7) =492724a(8) =5068915a(9) =52955950a(10) =560198962a(11) =5987822380a(12) =64563867454a(13) =701383563388
External references
- oeis: A194724