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

Author

Reinhard Zumkeller, Feb 20 2003

Keywords

• nonn
• base

Comments

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

Examples

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

Links

• Ivan Neretin, Table of n, a(n) for n = 1..8192
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A080541, A080544.

Programs

Mathematica

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