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 A055967 #5 Oct 28 2019 11:53:28
%S A055967 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,19,0,-19,-38,-57,-76,-95,
%T A055967 -114,-133,-152,-171,-190,-209,-228,-247,-266,-285,-304,-323,-342,38,
%U A055967 19,0,-19,-38,-57,-76,-95,-114,-133,-152,-171,-190,-209,-228,-247,-266,-285,-304,-323,57,38,19,0,-19,-38,-57,-76,-95
%N A055967 n - reversal of base 20 digits of n (written in base 10).
%C A055967 a(n) is a multiple of 19
%F A055967 a(n) =n-A056963(n)
%t A055967 Table[n-FromDigits[Reverse[IntegerDigits[n,20]],20],{n,0,70}] (* _Harvey P. Dale_, Oct 28 2019 *)
%Y A055967 Cf. A056965.
%K A055967 base,sign
%O A055967 0,21
%A A055967 _Henry Bottomley_, Jul 18 2000