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 A055955 #8 Oct 13 2021 00:51:34
%S A055955 0,0,0,0,0,0,0,6,0,-6,-12,-18,-24,-30,12,6,0,-6,-12,-18,-24,18,12,6,0,
%T A055955 -6,-12,-18,24,18,12,6,0,-6,-12,30,24,18,12,6,0,-6,36,30,24,18,12,6,0,
%U A055955 48,0,-48,-96,-144,-192,-240,48,0,-48,-96,-144,-192,-240,48,0,-48,-96,-144,-192,-240,48,0,-48,-96,-144,-192,-240
%N A055955 a(n) = n - reversal of base 7 digits of n (written in base 10).
%C A055955 a(n) is a multiple of 6.
%F A055955 a(n) = n - A030106(n).
%t A055955 Table[n-FromDigits[Reverse[IntegerDigits[n,7]],7],{n,0,80}] (* _Harvey P. Dale_, Jul 22 2015 *)
%Y A055955 Cf. A030106, A056965.
%K A055955 base,sign
%O A055955 0,8
%A A055955 _Henry Bottomley_, Jul 18 2000