# A143701 (b-file synthesized from sequence entry) 1 1 2 3 3 7 4 15 5 27 6 63 7 125 8 243 9 343 10 999 11 1805 12 3721 13 8181 14 16335 15 32761 16 65533 17 112847 18 190269 19 519375 20 1046875 21 1953125 22 4192479 23 8385125 24 16775019 25 24398405 26 66976875 27 134216625