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 A342345 #11 Mar 10 2021 16:32:21 %S A342345 3,33,363,36663,6306036,63066666036,6304963866683694036, %T A342345 6304963866689998999866683694036 %N A342345 a(1) = 3, a(n) = smallest palindromic nontrivial multiple of a(n-1) containing all decimal digits of a(n-1). %C A342345 Differs from A082778 at a(5). a(n) <= (10^A055642(a(n-1))+1)*a(n-1). 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). %e A342345 a(4) = 3663 is a palindromic multiple of a(3) = 363 and contains 2 '3' and 1 '6', all the digits of a(3). %Y A342345 Cf. A055642, A082778. %K A342345 nonn,base,more %O A342345 1,1 %A A342345 _Chai Wah Wu_, Mar 08 2021 %E A342345 a(8) from _Martin Ehrenstein_, Mar 10 2021