A319726 Write n in 9-ary, sort digits into decreasing order.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 19, 28, 37, 46, 55, 64, 73, 18, 19, 20, 29, 38, 47, 56, 65, 74, 27, 28, 29, 30, 39, 48, 57, 66, 75, 36, 37, 38, 39, 40, 49, 58, 67, 76, 45, 46, 47, 48, 49, 50, 59, 68, 77, 54, 55, 56, 57, 58, 59, 60, 69, 78, 63, 64, 65, 66, 67, 68, 69

Offset: 0

Author

Seiichi Manyama, Sep 26 2018

Keywords

• nonn
• base
• look
• easy

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..6560

Crossrefs

b-ary: A073138 (b=2), A319651 (b=3), A319720 (b=4), A319722 (b=5), A319723 (b=6), A319724 (b=7), A319725 (b=8), this sequence (b=9), A004186 (b=10).

Cf. A165110, A319657.

Programs

Mathematica

Table[FromDigits[Reverse[Sort[IntegerDigits[n,9]]],9],{n,0,70}] (* Harvey P. Dale, Oct 26 2022 *)

PARI

a(n) = fromdigits(vecsort(digits(n, 9), , 4), 9); \\ Michel Marcus, Sep 26 2018

Ruby

def A(k, n)
  (0..n).map{|i| i.to_s(k).split('').sort.reverse.join.to_i(k)}
end
p A(9, 100)

Formula

n <= a(n) < 9n. - Charles R Greathouse IV, Aug 07 2024