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 A329764 #8 Dec 16 2019 20:09:18 %S A329764 1,3,15,75,375,9375,159375,71559375,1195399359375,353915911333359375, %T A329764 51915571117579153359375,753315397517553377717399173359375, %U A329764 3319771735775931191533111595353537393933359375 %N A329764 a(1) = 1; thereafter a(n+1) > a(n) is the smallest multiple of a(n) using only odd digits but not divisible by 9. %C A329764 Equivalently, the sequence is defined as a(1) = 1, a(2) = 3, a(3) = 15, and for n > 2, a(n+1) > a(n) is the smallest multiple of a(n) using only odd digits. All terms besides a(1) and a(2) are divisible by 5. %Y A329764 Cf. A329762, A078221, A078223. %K A329764 nonn,base %O A329764 1,2 %A A329764 _Chai Wah Wu_, Dec 04 2019