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 A105647 #31 Jan 10 2023 01:16:48 %S A105647 2,5,25,52,55,222,252,255,552,555,2222,5222,5252,5255,22222,22252, %T A105647 22522,22525,22555,25222,52222,55222,55522,55525,55552,55555,222522, %U A105647 225222,225225,225522,252222,252225,522222,2225222,2225252,2225255,5222225,5222522,5225222 %N A105647 Lexicographically earliest sequence of increasing numbers whose digits satisfy the "Fractal Jump" rule using only the digits 2 and 5: keep the first digit "d" of the sequence, then jump over the next "d" digits and keep the digit "e" on which you have landed. Jump now over the next "e" digits and keep the digit "f" on which you have landed, etc. The succession "def..." of kept digits is the sequence itself. %H A105647 Tyler Busby, <a href="/A105647/b105647.txt">Table of n, a(n) for n = 1..200</a> %e A105647 The sequence and the "kept" digits begin %e A105647 2, 5, 25, 52, 55, 222, 252, 255, 552, ... %e A105647 ^ ^ ^ ^ ^ %e A105647 2 5 2 5 5 %Y A105647 Cf. A105395, A105396, A105397, A105398. %K A105647 base,easy,nonn %O A105647 1,1 %A A105647 _Eric Angelini_ and _Alexandre Wajnberg_, May 03 2005 %E A105647 Corrected and extended by _Tyler Busby_, Jan 08 2023