# A084508 (b-file synthesized from sequence entry) 0 0 1 1 2 3 3 9 4 33 5 129 6 513 7 2049 8 8193 9 32769 10 131073 11 524289 12 2097153 13 8388609 14 33554433 15 134217729 16 536870913 17 2147483649 18 8589934593 19 34359738369 20 137438953473 21 549755813889 22 2199023255553 23 8796093022209 24 35184372088833