8x9長軸前半
Table[sum[C(2n-1+C(0,30mod n)-C(0,n-2)-2C(0,n-5)-3C(0,n-9)-3C(1,n-13),k-1),{n,1,15}],{k,15,15}]

{148675947}

8x9長軸後半
Table[sum[C(2n-1-7C(0,n-20)+C(0,n-21)-C(1,n-23)-C(1,n-25)-C(0,n-27)+C(0,n-28),k-1),{n,16,35}],{k,15,15}]

{403841194852891}

{148675947}+{403841194852891}={403841343528838}


>>488
8 * 9 [15]と一致