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 A053980 #35 Apr 13 2018 11:14:30
%S A053980 1,5,98,127,923,5474,16490,25355,37910,85150,1033216,2290644,7844861,
%T A053980 11170684,18884358,21481832,35060787,52399788,201059261,261533994,
%U A053980 9939708446,211698940106,3030068839686,4326424644987,6082687570463
%N A053980 Engel expansion of zeta(3) = 1.20206... .
%C A053980 Cf. A006784 for definition of Engel expansion.
%D A053980 F. Engel, Entwicklung der Zahlen nach Stammbruechen, Verhandlungen der 52. Versammlung deutscher Philologen und Schulmaenner in Marburg, 1913, pp. 190-191.
%H A053980 G. C. Greubel, <a href="/A053980/b053980.txt">Table of n, a(n) for n = 1..1000</a>
%H A053980 F. Engel, <a href="/A006784/a006784.pdf">Entwicklung der Zahlen nach Stammbruechen</a>, Verhandlungen der 52. Versammlung deutscher Philologen und Schulmaenner in Marburg, 1913, pp. 190-191. English translation by Georg Fischer, included with his permission.
%H A053980 P. Erdős and Jeffrey Shallit, <a href="http://www.numdam.org/item?id=JTNB_1991__3_1_43_0">New bounds on the length of finite Pierce and Engel series</a>, Sem. Theor. Nombres Bordeaux (2) 3 (1991), no. 1, 43-53.
%H A053980 <a href="/index/El#Engel">Index entries for sequences related to Engel expansions</a>
%t A053980 EngelExp[ A_, n_ ] := Join[ Array[ 1&, Floor[ A ] ], First@Transpose@NestList[ {Ceiling[ 1/Expand[ #[[ 1 ] ]#[[ 2 ] ]-1 ] ], Expand[ #[[ 1 ] ]#[[ 2 ] ]-1 ]}&, {Ceiling[ 1/(A-Floor[ A ]) ], A-Floor[ A ]}, n-1 ] ]
%Y A053980 Cf. A006784, A028254, A028257.
%Y A053980 Cf. A002117, A067912.
%K A053980 nonn,easy,nice
%O A053980 1,2
%A A053980 _Jeppe Stig Nielsen_, Apr 02 2000
%E A053980 More terms and additional comments from _Mitch Harris_, Jan 15 2001