A080543 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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 *)