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 A070152 #31 Jan 29 2022 12:15:56
%S A070152 1,2,4,13,18,33,35,7,78,133,178,228,273,388,710,1333,1701,1778,2737,
%T A070152 3273,3563,3087,3478,12488,13333,14208,17778,31463,36993,5338,7063,
%U A070152 9063,12643,15238,17147,22448,23788,27313,29058,34488,36763,38788,43273,50813,53578
%N A070152 Take pairs (x,y) with Sum_{j = x..y} j = concatenation of x and y. Sort pairs on y then x. This sequence gives x of each pair.
%C A070152 From _Bernard Schott_, Jan 26 2022: (Start)
%C A070152 Some subsequences, from Diophante and Crux Mathematicorum:
%C A070152 {(2*10^m-5)/15, m >= 1} = 1, 13, 133, 1333, ... = A097166.
%C A070152 {2*(4*10^m+5)/45, m >= 1} = 2, 18, 178, 1778, ...
%C A070152 {13*(26*100^m-125)/12375, m >= 2} = 273, 27313, 2731313, ... (End)
%H A070152 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 A070152 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 A070152 1+...+5 = 15; 2+...+7 = 27; 4+...+29 = 429; 13+...+53 = 1353; 18+...+63 = 1863.
%e A070152 133+...+533 = 133533.
%e A070152 273+...+2353 = 2732353.
%Y A070152 Cf. A070153, A071297, A186074.
%Y A070152 Subsequence: A097166.
%K A070152 nonn,base
%O A070152 1,2
%A A070152 _Lekraj Beedassy_, May 06 2002
%E A070152 More terms from _David W. Wilson_, Jun 04 2002
%E A070152 Name edited by _Michel Marcus_, Jan 29 2022