Number of configurations of Sam Loyd's sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square at one of the 8 non-corner boundary squares.

A090165

Number of configurations of Sam Loyd's sliding block 15-puzzle that require a minimum of n moves to be reached, starting with the empty square at one of the 8 non-corner boundary squares.

Terms

    a(0) =1a(1) =3a(2) =6a(3) =14a(4) =32a(5) =66a(6) =134a(7) =280a(8) =585a(9) =1214a(10) =2462a(11) =4946a(12) =9861a(13) =19600a(14) =38688a(15) =76086a(16) =148435a(17) =288098a(18) =554970a(19) =1062628a(20) =2016814a(21) =3800682a(22) =7093209a(23) =13127364a(24) =24053454a(25) =43657576a(26) =78382622a(27) =139237375

External references