A135903 Column 0 of triangle A135902; also equals column 2 of triangle A135902 (shift right).
1, 1, 3, 15, 102, 860, 8548, 97094, 1234324, 17302880, 264503376, 4371376170, 77567318328, 1469440535360, 29578625457508, 630090773216810, 14155112389880376, 334337856517696916, 8280411098557369468
Offset: 0