Number of 6-step knight's tours on an (n+2) X (n+2) board summed over all starting positions.

Terms

a(0) =16a(1) =800a(2) =8352a(3) =34448a(4) =91328a(5) =186544a(6) =322528a(7) =498320a(8) =712080a(9) =963008a(10) =1251104a(11) =1576368a(12) =1938800a(13) =2338400a(14) =2775168a(15) =3249104a(16) =3760208a(17) =4308480a(18) =4893920a(19) =5516528a(20) =6176304a(21) =6873248a(22) =7607360a(23) =8378640a(24) =9187088a(25) =10032704a(26) =10915488a(27) =11835440a(28) =12792560a(29) =13786848