Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #27 Sep 08 2022 08:44:50
%S 1,2,4,8,16,23,46,128,256,125,124,248,469,1289,13468,23678,35566,
%T 11237,122446,224588,145678,122579,134449,368888,11266777,23334455,
%U 1466788,112234778,234455668,12356789,112344778,1234446788,2244667999
%N Arrange digits of 2^n in ascending order.
%C Leading zeros are discarded (e.g., 2^23 = 8388608 -> 0368888 becomes 368888).
%H Alois P. Heinz, <a href="/A028909/b028909.txt">Table of n, a(n) for n = 0..3600</a>
%p a:= n-> parse(cat(sort(convert(2^n, base, 10))[])):
%p seq(a(n), n=0..50); # _Alois P. Heinz_, Jan 21 2020
%t Table[FromDigits[Sort[IntegerDigits[2^n]]],{n,0,40}] (* _Harvey P. Dale_, Aug 20 2013 *)
%o (Magma) [Seqint(Reverse(Sort(Intseq(2^n)))):n in [0..35]]; // _Vincenzo Librandi_, Jan 22 2020
%o (Python)
%o def A028909(n):
%o return int(''.join(sorted(str(2**n)))) # _Chai Wah Wu_, Feb 19 2021
%Y 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 nonn,base
%O 0,2
%A _N. J. A. Sloane_
%E More terms from _Patrick De Geest_, April 1998