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 A028909 #29 Jul 05 2025 16:34:27
%S A028909 1,2,4,8,16,23,46,128,256,125,124,248,469,1289,13468,23678,35566,
%T A028909 11237,122446,224588,145678,122579,134449,368888,11266777,23334455,
%U A028909 1466788,112234778,234455668,12356789,112344778,1234446788,2244667999
%N A028909 Arrange digits of 2^n in ascending order.
%C A028909 Leading zeros are discarded (e.g., 2^23 = 8388608 -> 0368888 becomes 368888).
%H A028909 Alois P. Heinz, <a href="/A028909/b028909.txt">Table of n, a(n) for n = 0..3600</a>
%p A028909 a:= n-> parse(cat(sort(convert(2^n, base, 10))[])):
%p A028909 seq(a(n), n=0..50); # _Alois P. Heinz_, Jan 21 2020
%t A028909 Table[FromDigits[Sort[IntegerDigits[2^n]]],{n,0,40}] (* _Harvey P. Dale_, Aug 20 2013 *)
%o A028909 (Magma) [Seqint(Reverse(Sort(Intseq(2^n)))):n in [0..35]]; // _Vincenzo Librandi_, Jan 22 2020
%o A028909 (Python)
%o A028909 def A028909(n):
%o A028909 return int(''.join(sorted(str(2**n)))) # _Chai Wah Wu_, Feb 19 2021
%Y A028909 The following are parallel families: A000079 (2^n), A004094 (2^n reversed), A028909 (2^n sorted up), A028910 (2^n sorted down), A036447 (double and reverse), A057615 (double and sort up), A263451 (double and sort down); A000244 (3^n), A004167 (3^n reversed), A321540 (3^n sorted up), A321539 (3^n sorted down), A163632 (triple and reverse), A321542 (triple and sort up), A321541 (triple and sort down).
%K A028909 nonn,base
%O A028909 0,2
%A A028909 _N. J. A. Sloane_
%E A028909 More terms from _Patrick De Geest_, Apr 1998