Number of length n reversible string structures that are not palindromic using exactly four different colors.

A327611

Number of length n reversible string structures that are not palindromic using exactly four different colors.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =1a(4) =6a(5) =37a(6) =182a(7) =876a(8) =3920a(9) =17175a(10) =73030a(11) =306296a(12) =1266916a(13) =5198207a(14) =21180642a(15) =85909216a(16) =347179440a(17) =1399443775a(18) =5629876910a(19) =22616222616a(20) =90754709276a(21) =363889980927

External references