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 A177769 #28 Jan 27 2024 07:51:41 %S A177769 111,222,333,444,555,666,777,888,999,1110,1221,1332,1443,1554,1665, %T A177769 1776,1887,1998,2109,2220,2331,2442,2553,2664,2775,2886,2997,3108, %U A177769 3219,3330,3441,3552,3663,3774,3885,3996,4107,4218,4329,4440,4551,4662,4773,4884,4995,5106 %N A177769 a(n) = 111*n. %C A177769 The reference contains also sequences A102807, A109344, A075415, and A109492. %H A177769 Vincenzo Librandi, <a href="/A177769/b177769.txt">Table of n, a(n) for n = 1..10000</a> %H A177769 Émile Fourrey, <a href="https://gallica.bnf.fr/ark:/12148/bpt6k875411n/f21.item">Le nombre 37</a>, Récreations arithmétiques, 1899 and later, Vuibert, Paris, page 11. %H A177769 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1). %F A177769 G.f.: 111*x/(x-1)^2. %F A177769 a(n) = 2*a(n-1) - a(n-2). %F A177769 a(n) = a(n-1) + 111. %F A177769 E.g.f.: 111*x*exp(x). - _Stefano Spezia_, Sep 15 2023 %o A177769 (Magma) [111*n: n in [1..50]]; // _Vincenzo Librandi_, Aug 04 2011 %Y A177769 Cf. A075415, A102807, A109344, A109492. %K A177769 nonn,easy %O A177769 1,1 %A A177769 _Paul Curtz_, May 13 2010