This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A281085 #7 Jan 15 2017 11:45:41 %S A281085 0,0,1,1,13,9,29,59,1163,569,4861,21341,58301,79139,619181,260041, %T A281085 1715839,1808487,10190221,116220883,32925391,966183,13920029, %U A281085 455451475,4597423223,1536962359,64517796001,154777722503,235091155703,3714867879427,6975593267347,75441657715841 %N A281085 Numerator of sum of reciprocals of numbers less than n that do not divide n. %F A281085 a(n) = numerator(H_n - Sum_{d|n} 1/d), where H_n is the n-th harmonic number. %F A281085 a(n) = numerator(A001008(n)/A002805(n) - A000203(n)/n). %F A281085 Numerators of coefficients in expansion of -log(1 - x)/(1 - x) - Sum_{k>=1} log(1/(1 - x^k)). %e A281085 a(6) = 9 because 6 has 4 divisors {1,2,3,6} therefore 2 non-divisors {4,5} and 1/4 + 1/5 = 9/20. %e A281085 0, 0, 1/2, 1/3, 13/12, 9/20, 29/20, 59/70, 1163/840, 569/504, 4861/2520, 21341/27720, 58301/27720, 79139/51480, 619181/360360, 260041/180180, ... %t A281085 Table[Numerator[HarmonicNumber[n] - DivisorSigma[-1, n]], {n, 1, 32}] %t A281085 Table[Numerator[HarmonicNumber[n] - DivisorSigma[1, n]/n], {n, 1, 32}] %Y A281085 Cf. A000203, A001008, A002805, A017665, A017666, A024816, A277790, A281086 (denominators). %K A281085 nonn,frac %O A281085 1,5 %A A281085 _Ilya Gutkovskiy_, Jan 14 2017