A028909 Arrange digits of 2^n in ascending order.

1, 2, 4, 8, 16, 23, 46, 128, 256, 125, 124, 248, 469, 1289, 13468, 23678, 35566, 11237, 122446, 224588, 145678, 122579, 134449, 368888, 11266777, 23334455, 1466788, 112234778, 234455668, 12356789, 112344778, 1234446788, 2244667999

Offset

0,2

Comments

Leading zeros are discarded (e.g., 2^23 = 8388608 -> 0368888 becomes 368888).

Links

Alois P. Heinz, Table of n, a(n) for n = 0..3600

Maple

a:= n-> parse(cat(sort(convert(2^n, base, 10))[])):
seq(a(n), n=0..50);  # Alois P. Heinz, Jan 21 2020

Mathematica

Table[FromDigits[Sort[IntegerDigits[2^n]]], {n, 0, 40}] (* Harvey P. Dale, Aug 20 2013 *)

Prog

(Magma) [Seqint(Reverse(Sort(Intseq(2^n)))):n in [0..35]]; // Vincenzo Librandi, Jan 22 2020
(Python)
def A028909(n):
    return int(''.join(sorted(str(2**n)))) # Chai Wah Wu, Feb 19 2021

Crossrefs

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).

Sequence in context: A371880 A057615 A018416 * A108567 A354754 A261890

Adjacent sequences: A028906 A028907 A028908 * A028910 A028911 A028912

Keyword

nonn,base

Author

N. J. A. Sloane

Extensions

More terms from Patrick De Geest, April 1998

Status

approved