Number of branches of length 1 in all hex trees with n edges.

A126323

Number of branches of length 1 in all hex trees with n edges.

Terms

    a(0) =0a(1) =3a(2) =2a(3) =15a(4) =80a(5) =399a(6) =1956a(7) =9546a(8) =46552a(9) =227100a(10) =1108698a(11) =5417127a(12) =26490312a(13) =129645027a(14) =634978290a(15) =3112277265a(16) =15264984260a(17) =74919716085a(18) =367926876630

External references