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 A088404 #15 Jul 21 2025 00:01:17 %S A088404 1,10,55,100,505,550,1000,5005,5050,5500,10000,50005,50050,50500, %T A088404 55000,100000,500005,500050,500500,505000,550000,1000000,5000005, %U A088404 5000050,5000500,5005000,5050000,5500000,10000000,50000005,50000050,50000500 %N A088404 a(n) = A069537(n)/2. %C A088404 Sequence comprises all integers that are the arithmetic mean of two powers of ten, A011557. - _Lewis Chen_, Jul 17 2025 %H A088404 Alois P. Heinz, <a href="/A088404/b088404.txt">Table of n, a(n) for n = 1..10000</a> %Y A088404 Cf. A069537. %K A088404 nonn,easy %O A088404 1,2 %A A088404 _Ray Chandler_, Sep 29 2003