A026650 a(n) = T(2n,n-1), T given by A026648.

1, 6, 21, 108, 370, 1908, 6587, 34248, 119142, 623700, 2182818, 11487528, 40391988, 213451560, 753295635, 3993910416, 14136717574, 75152083716, 266650874678, 1420670333640, 5050926317724, 26960309526744, 96015725922014

Offset: 1

Author

Clark Kimberling

Keywords

• nonn