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 A243590 #8 Jun 11 2014 22:51:24 %S A243590 2,4,6,8,0,2,4,6,8,2,22,42,62,82,2,22,42,62,82,4,24,44,64,84,4,24,44, %T A243590 64,84,6,26,46,66,86,6,26,46,66,86,8,28,48,68,88,8,28,48,68,88,0,20, %U A243590 40,60,80,0,20,40,60,80,2,22,42,62,82,2,22,42,62,82,4,24 %N A243590 Numbers returned when each digit of n is replaced by the sum modulo 10 of the digits to its (wrapped) left and (wrapped) right. %C A243590 Numbers returned by the following function: take the t digits of n, d(1)..d(t), and replace each with the sum d(i) = (d(i-1) + d(i+1)) mod 10, where (i-1 = 0) maps to t and (i+1 > t) maps to 1. %H A243590 Anthony Sand, <a href="/A243590/b243590.txt">Table of n, a(n) for n = 1..1000</a> %F A243590 for digits d(1)..d(t), d(i) = (d(i-1) + d(i+1)) mod 10, where (i-1 = 0) -> t, (i+1 > t) -> 1. %e A243590 For 1, the function returns (1 + 1) mod 10 = 2. %e A243590 For 5, the function returns (5 + 5) mod 10 = 0. %e A243590 For 125, the initial digits are (1,2,5). %e A243590 d(1) <- (d(3) + d(2)) mod 10 = (5 + 2) mod 10 = 7; d(2) <- (d(1) + d(3)) mod 10 = (1 + 5) mod 10 = 6; d(3) <- (d(2) + d(1)) mod 10 = (2 + 1) mod 10 = 3. %e A243590 The function returns (7,6,3) = 763. %Y A243590 Cf. A055120, A035327. %K A243590 nonn,base %O A243590 1,1 %A A243590 _Anthony Sand_, Jun 07 2014