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 A193434 #42 Jul 23 2024 20:21:19
%S A193434 45,495,4545,4995,45045,49995,450045,454545,495495,499995,4500045,
%T A193434 4549545,4950495,4999995,45000045,45045045,45454545,45499545,49500495,
%U A193434 49545495,49954995,49999995,450000045,450495045,454504545,454999545,495000495,495495495,499504995
%N A193434 6*n/5 = (n written backwards), n > 0.
%H A193434 Ray Chandler, <a href="/A193434/b193434.txt">Table of n, a(n) for n = 1..10000</a> (first 4000 terms from Arkadiusz Wesolowski)
%F A193434 a(n) = 45*A057148(n+1). - _Ray Chandler_, Oct 09 2017
%e A193434 495 belongs to this sequence because 6*495/5 = 594.
%t A193434 Rest@Select[FromDigits /@ Tuples[{0, 45}, 8], IntegerDigits[6*#/5] == Reverse@IntegerDigits[#] &] (* _Arkadiusz Wesolowski_, Aug 14 2012 *)
%o A193434 (Python)
%o A193434 def A193434(n):
%o A193434 a = 1<<(m:=n+1).bit_length()-2
%o A193434 s = bin(a|(m&a-1))[2:]
%o A193434 return 45*int(s+(s[::-1] if a&m else s[-2::-1])) # _Chai Wah Wu_, Jul 23 2024
%Y A193434 Cf. A001232, A008918, A057148, A101705.
%K A193434 base,nonn
%O A193434 1,1
%A A193434 _Arkadiusz Wesolowski_, Aug 01 2011