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 A342346 #20 Feb 12 2024 02:06:39 %S A342346 4,44,484,48884,8408048,84088888048,8408888888888888048, %T A342346 84088888888888888888888888888888048 %N A342346 a(1) = 4, a(n) = smallest palindromic nontrivial multiple of a(n-1) containing all decimal digits of a(n-1). %C A342346 Differs from A082779 at a(5). %C A342346 a(n) <= (10^A055642(a(n-1))+1)*a(n-1). %C A342346 If a(n-1) > 10 and the last digit of a(n-1) <= 4, then a(n) <= (10^(A055642(a(n-1))-1)+1)*a(n-1). %C A342346 For n = 5..8, we have a(n) = 7568 * A002275(2^(n-3)), and it follows that a(9) <= 7568 * A002275(64). Conjecture: for all n >= 5, a(n) = 7568 * A002275(2^(n-3)). Note that 7568 is a term of A370052 and A370053. - _Max Alekseyev_, Feb 08 2024 %e A342346 a(3) = 484 is a palindromic multiple of a(2) = 44 and contains two '4', all the digits of a(2). %Y A342346 Cf. A055642, A082779, A370052, A370053. %K A342346 nonn,base,more %O A342346 1,1 %A A342346 _Chai Wah Wu_, Mar 08 2021 %E A342346 a(8) from _Max Alekseyev_, Feb 07 2024