A319720 Write n in 4-ary, sort digits into decreasing order.

0, 1, 2, 3, 4, 5, 9, 13, 8, 9, 10, 14, 12, 13, 14, 15, 16, 20, 36, 52, 20, 21, 37, 53, 36, 37, 41, 57, 52, 53, 57, 61, 32, 36, 40, 56, 36, 37, 41, 57, 40, 41, 42, 58, 56, 57, 58, 62, 48, 52, 56, 60, 52, 53, 57, 61, 56, 57, 58, 62, 60, 61, 62, 63, 64, 80, 144, 208, 80, 84

Offset

0,3

Links

Seiichi Manyama, Table of n, a(n) for n = 0..4095

Formula

n <= a(n) < 4n. - Charles R Greathouse IV, Aug 07 2024

Mathematica

Table[FromDigits[ReverseSort[IntegerDigits[n, 4]], 4], {n, 0, 100}] (* Paolo Xausa, Aug 07 2024 *)

Prog

(Ruby)
def A(k, n)
  (0..n).map{|i| i.to_s(k).split('').sort.reverse.join.to_i(k)}
end
p A(4, 100)
(PARI) a(n) = fromdigits(vecsort(digits(n, 4), , 4), 4); \\ Michel Marcus, Sep 26 2018

Crossrefs

b-ary: A073138 (b=2), A319651 (b=3), this sequence (b=4), A319722 (b=5), A319723 (b=6), A319724 (b=7), A319725 (b=8), A319726 (b=9), A004186 (b=10).

Cf. A165012, A319652.

Sequence in context: A101526 A264994 A331364 * A140298 A253181 A107365

Adjacent sequences: A319717 A319718 A319719 * A319721 A319722 A319723

Keyword

nonn,base,easy

Author

Seiichi Manyama, Sep 26 2018

Status

approved