A331274 a(n) is the greatest binary anagram of n not yet in the sequence.

1, 2, 3, 4, 6, 5, 7, 8, 12, 10, 14, 9, 13, 11, 15, 16, 24, 20, 28, 18, 26, 25, 30, 17, 22, 21, 29, 19, 27, 23, 31, 32, 48, 40, 56, 36, 52, 50, 60, 34, 49, 44, 58, 42, 57, 54, 62, 33, 41, 38, 53, 37, 51, 46, 61, 35, 45, 43, 59, 39, 55, 47, 63, 64, 96, 80, 112

Offset: 1

Author

Rémy Sigrist, Jan 13 2020

Keywords

• nonn
• look
• base

Comments

Leading zeros are ignored.

This sequence is a self-inverse permutation of the natural numbers.

Examples

			The first terms, in decimal and in binary, are:
  n   a(n)  bin(n)  bin(a(n))
  --  ----  ------  ---------
   1     1       1          1
   2     2      10         10
   3     3      11         11
   4     4     100        100
   5     6     101        110
   6     5     110        101
   7     7     111        111
   8     8    1000       1000
   9    12    1001       1100
  10    10    1010       1010
  11    14    1011       1110
  12     9    1100       1001
  13    13    1101       1101
  14    11    1110       1011
  15    15    1111       1111
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..8192
• Rémy Sigrist, Colored scatterplot of the first 2^13 terms (where the color is function of the Hamming weight of n)
• Rémy Sigrist, PARI program for A331274
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A007318, A187769, A298847, A331275 (ternary analog).

Programs

PARI

\\ See Links section.

Formula

a(A187769(n, k)) = A187769(n, A007318(n-1)+1-k) for any n > 0 and k = 1..A007318(n-1).