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 A284803 #6 Jan 05 2020 14:55:55
%S A284803 5,4,3,2,1,0,34,28,22,16,10,4,33,27,21,15,9,3,32,26,20,14,8,2,31,25,
%T A284803 19,13,7,1,30,24,18,12,6,0,214,178,142,106,70,34,208,172,136,100,64,
%U A284803 28,202,166,130,94,58,22,196,160,124,88,52,16,190,154,118,82,46
%N A284803 Write in base k, complement, reverse. Case k = 6.
%e A284803 a(13) = 27 because 13 in base 6 is 21, its complement in base 6 is 34 and the digit reverse is 43 that is 27 in base 10.
%p A284803 P:=proc(q,h) local a,b,k,n; print(h-1); for n from 1 to q do a:=convert(n,base,h); b:=0;
%p A284803 for k from 1 to nops(a) do a[k]:=h-1-a[k]; b:=h*b+a[k]; od; print(b); od; end: P(10^2,6);
%t A284803 Table[FromDigits[Reverse[5-IntegerDigits[n,6]],6],{n,0,70}] (* _Harvey P. Dale_, Jan 05 2020 *)
%Y A284803 Cf. A036044, A267193, A284804.
%K A284803 nonn,base,easy
%O A284803 0,1
%A A284803 _Paolo P. Lava_, Apr 03 2017
%E A284803 Example corrected by _Harvey P. Dale_, Jan 05 2020