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 A070153 #35 Jan 29 2022 12:15:50
%S A070153 5,7,29,53,63,88,91,119,403,533,623,2148,2353,2813,3835,5333,6076,
%T A070153 6223,7889,8728,9163,25039,26603,51513,53333,55168,62223,85338,93633,
%U A070153 103463,119063,134938,159518,175238,185979,213073,219413,235313,242818,264888
%N A070153 Take pairs (x,y) with Sum_{j = x..y} j = concatenation of x and y. Sort pairs on y then x. This sequence gives y of each pair.
%C A070153 From _Bernard Schott_, Jan 26 2022: (Start)
%C A070153 Some subsequences, from Diophante and Crux Mathematicorum:
%C A070153 {(8*10^m-5)/15, m >= 1} = 5, 53, 533, 5333, ... (A350995).
%C A070153 {7*(4*10^m+5)/45, m >= 1} = 7, 63, 623, 6223, ...
%C A070153 {13*(224*100^m-125)/12375, m >= 2} = 2353, 235313, 23531313, ... (End)
%H A070153 Diophante, <a href="http://www.diophante.fr/problemes-par-themes/arithmetique-et-algebre/a1-pot-pourri/1024-a1945-concatenations-en-tous-genres">A1945 - Concaténations en tous genres</a> (in French).
%H A070153 R. Hoshino, <a href="http://cms.math.ca/crux/v27/n1/public_page34-47.pdf">Astonishing Pairs of Numbers</a>, Crux Mathematicorum 27(1), 2001, p. 39-44.
%e A070153 1+...+5 = 15; 2+...+7 = 27; 4+...+29 = 429; 13+...+53 = 1353; 18+...+63 = 1863.
%e A070153 133+...+533 = 133533.
%e A070153 178+...+623 = 178623.
%Y A070153 Cf. A070152, A071297, A097166, A186074.
%Y A070153 Cf. A350995 (is a subsequence).
%K A070153 nonn,base
%O A070153 1,1
%A A070153 _Lekraj Beedassy_, May 06 2002
%E A070153 More terms from _David W. Wilson_, Jun 04 2002
%E A070153 Name edited by _Michel Marcus_, Jan 29 2022