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 A131766 #8 Jul 31 2025 02:43:50 %S A131766 0,0,0,0,0,18,36,54,72,180,378,576,774,972,2970,4968,6966,8964,19962, %T A131766 39960,59958,79956,99954,299952,499950,699948,899946,1999944,3999942, %U A131766 5999940,7999938,9999936,29999934,49999932,69999930,89999928,199999926,399999924,599999922 %N A131766 a(n) = A131668(n) - (2*n+1). %C A131766 Digital sums: 9*A002266. %H A131766 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1,0,0,0,0,0,0,100,-200,100). %Y A131766 Cf. A002266, A131668, A131871. %K A131766 nonn,base,easy %O A131766 0,6 %A A131766 _Paul Curtz_, Oct 04 2007 %E A131766 a(30) corrected and more terms from _Georg Fischer_, Jul 30 2025