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 A180403 #11 Dec 17 2019 05:35:40
%S A180403 1,-1,-5,-3,-93,95,-793,-211,-5853,27003,-215955,57459,-3518265,
%T A180403 3602027,16811055,-4362627,-1846943453,293601363,-14911085359,
%U A180403 4487888279,144251733709,245294787521,-1936010885087,228009405371,-11179552565305,63485965327535,-48562641580527
%N A180403 Numerator in Moebius transform of A001790/A046161.
%C A180403 Consider a lower triangular matrix T(n,k) defined by T(n,1)=A001790/A046161, k>1: T(n,k) = (Sum_{i=1..k-1} T(n-i,k-1)) - (Sum_{i=1..k-1} T(n-i,k)). The first column in the matrix inverse of T(n,k) will have the fraction A180403/A046161 in its first column.
%C A180403 The sequence considers the Moebius transform 1, -1/2, -5/8, -3/16, -93/128, ... of the sequence A001790(n-1)/A046161(n-1), i.e., assigning offset 1 to A001790 and A046161. - _R. J. Mathar_, Apr 22 2011
%F A180403 Lambert series: Sum_{n >= 1} (A180403(n)/A046161(n))*x^n/(1-x^n) = x/sqrt(1-x). - _Mats Granvik_, Sep 07 2010
%Y A180403 Cf. A001790, A046161 (denominators).
%K A180403 frac,sign
%O A180403 1,3
%A A180403 _Mats Granvik_, Sep 02 2010
%E A180403 Signs of terms corrected by _Mats Granvik_, Sep 05 2010
%E A180403 Corrected and edited by _Mats Granvik_, Oct 08 2010