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 A358257 #19 Dec 25 2022 15:04:36 %S A358257 0,5,5,8,8,8,1,1,1,4,4,4,7,7,7,0,0,0,3,3,3,6,6,6,9,9,2,2,2,5,5,5,8,8, %T A358257 8,1,1,1,4,4,4,7,7,7,0,0,0,3,3,3,6,6,6,9,9,9,2,2,2,5,5,5,8,8,8,1,1,1, %U A358257 4,4,4,7,7,7,0,0,0,3,3,3,6,6,6,9,9,9,2,2,2,5,5,8,8,8,1,1,1,4,4,4,7,7,7,0,0 %N A358257 The least significant digit of k such that 2^k, 5^k, 8^k start with the same digit. %C A358257 The sequence consists of groups of identical digits. The numbers representing each group, starting from the second group, form a cycle (5, 8, 1, 4, 7, 0, 3, 6, 9, 2). %F A358257 a(n) = A358197(n) mod 10. %F A358257 a(n) = A010879(A358197(n)). %e A358257 a(3) = A358197(3) mod 10 = 15 mod 10 = 5, %e A358257 a(4) = A358197(4) mod 10 = 98 mod 10 = 8, %e A358257 a(9) = A358197(9) mod 10 = 221 mod 10 = 1. %Y A358257 Cf. A010879, A358197. %K A358257 nonn,base %O A358257 1,2 %A A358257 _Alexander M. Domashenko_, Nov 05 2022