# A005628 (b-file synthesized from sequence entry) 0 0 1 0 2 0 3 0 4 2 5 6 6 20 7 60 8 176 9 510 10 1484 11 4314 12 12624 13 37126 14 109864 15 326958 16 978528 17 2943384 18 8895792 19 27001378 20 82281216 21 251636434 22 772101086 23 2376186784 24 7333094178 25 22688117658 26 70360646672 27 218678194238 28 681016789056