A080543 In binary representation: keep the first digit and rotate left the others twice.

1, 2, 3, 4, 5, 6, 7, 8, 12, 9, 13, 10, 14, 11, 15, 16, 20, 24, 28, 17, 21, 25, 29, 18, 22, 26, 30, 19, 23, 27, 31, 32, 36, 40, 44, 48, 52, 56, 60, 33, 37, 41, 45, 49, 53, 57, 61, 34, 38, 42, 46, 50, 54, 58, 62, 35, 39, 43, 47, 51, 55, 59, 63, 64, 68, 72, 76, 80, 84, 88, 92, 96

Offset

1,2

Comments

a(n) = A080541(A080541(n)); permutation of natural numbers with inverse = A080544: A080544(a(n)) = a(A080544(n)) = n.

Links

Ivan Neretin, Table of n, a(n) for n = 1..8192

Index entries for sequences that are permutations of the natural numbers

Example

a(20) = a('10100') = '100001' = 17; a(24) = a('11000') = '10010' = 18.

Mathematica

Table[FromDigits[Prepend[RotateLeft[Rest[IntegerDigits[n, 2]], 2], 1], 2], {n, 72}] (* Ivan Neretin, Aug 30 2015 *)

Crossrefs

Cf. A080541, A080544.

Sequence in context: A246025 A211699 A118600 * A285916 A119797 A032972

Adjacent sequences: A080540 A080541 A080542 * A080544 A080545 A080546

Keyword

nonn,base

Author

Reinhard Zumkeller, Feb 20 2003

Status

approved