A026886 T(2n,n+4), T given by A026769.
1, 10, 67, 380, 1978, 9814, 47391, 225590, 1067527, 5051454, 24001979, 114858924, 554704282, 2707092726, 13359365962, 66678605418, 336519708452, 1716476383658, 8842304168692, 45966748864706, 240938394287134, 1272300373503706
Offset: 4