# A152961 (b-file synthesized from sequence entry) 1 2 2 3 3 5 4 7 5 13 6 17 7 19 8 31 9 61 10 127 11 521 12 2281 13 3217 14 4253 15 9941 16 19937 17 21701 18 23209 19 44497 20 110503 21 216091 22 859433 23 1257787 24 3021377 25 6972593 26 13466917 27 20996011 28 30402457 29 32582657 30 42643801 31 57885161