# A019539 (b-file synthesized from sequence entry) 0 2 1 4 2 7 3 8 4 16 5 15 6 15 7 16 8 63 9 256 10 128 11 511 12 32 13 31 14 31 15 32 16 256 17 4095 18 1023 19 127 20 4095 21 524288 22 131072 23 255