A070152 - OEIS

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.

1, 2, 4, 13, 18, 33, 35, 7, 78, 133, 178, 228, 273, 388, 710, 1333, 1701, 1778, 2737, 3273, 3563, 3087, 3478, 12488, 13333, 14208, 17778, 31463, 36993, 5338, 7063, 9063, 12643, 15238, 17147, 22448, 23788, 27313, 29058, 34488, 36763, 38788, 43273, 50813, 53578

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OFFSET

1,2

COMMENTS

From Bernard Schott, Jan 26 2022: (Start)

Some subsequences, from Diophante and Crux Mathematicorum:

{(2*10^m-5)/15, m >= 1} = 1, 13, 133, 1333, ... = A097166.

{2*(4*10^m+5)/45, m >= 1} = 2, 18, 178, 1778, ...

{13*(26*100^m-125)/12375, m >= 2} = 273, 27313, 2731313, ... (End)

LINKS

Table of n, a(n) for n=1..45.

Diophante, A1945 - Concaténations en tous genres (in French).