Generating function = sum over all subsets S of the integers {0,1,2...} of 1/sum(1/x^n for n in S).

Terms

a(0) =1a(1) =2a(2) =3a(3) =7a(4) =11a(5) =25a(6) =44a(7) =94a(8) =176a(9) =367a(10) =703a(11) =1447a(12) =2820a(13) =5740a(14) =11307a(15) =22858a(16) =45280a(17) =91195a(18) =181364a(19) =364176a(20) =725941a(21) =1455473a(22) =2905063a(23) =5818958a(24) =11623598a(25) =23268350a(26) =46503053a(27) =93057123a(28) =186032424a(29) =372189177