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 A111881 #11 Jan 21 2025 03:25:53
%S A111881 1,1,29,1,103,253,1669,181,30791,849,452993,41003,94949,421117,
%T A111881 18358463,446801,124184839,30064511,80932487,19812817,211524139,
%U A111881 333707681,4757207109,2557825027,105920383973,14417396537,4649180818987
%N A111881 Numerators of row sums of array of ratios A111879(n,k)/A111880(n,k).
%F A111881 a(n) = numerator(Sum_{k=1..phi(n)-1} r(n, k)), with phi(n) = A000010(n) (Euler's totient function) and the ratios r(n, k) = A111879(n, k)/A111880(n, k).
%e A111881 The ratios a(n)/A069220(n) are: 1/2, 1/3, 29/12, 1/5, 103/20, 253/105, 1669/280, 181/63, 30791/2520, 849/385, ... (see the W. Lang link under A111879.)
%Y A111881 Cf. A111879, A111880.
%Y A111881 The denominators are given in A069220(n), n>=3.
%K A111881 nonn,easy,frac
%O A111881 3,3
%A A111881 _Wolfdieter Lang_, Aug 23 2005