a(n) = numerator(Sum_{k=1..n} (2^k-2)/k).

Terms

a(0) =0a(1) =1a(2) =3a(3) =13a(4) =25a(5) =137a(6) =245a(7) =871a(8) =517a(9) =4629a(10) =8349a(11) =45517a(12) =83317a(13) =1074679a(14) =1992127a(15) =7424789a(16) =13901189a(17) =78403447a(18) =147940327a(19) =280060651a(20) =531718651a(21) =11133725681a(22) =21243819521a(23) =40621501691a(24) =15565330735a(25) =388375065019a(26) =248882304985a(27) =479199924517a(28) =923951191477