A388055 The binary expansion of the n-th term of A074832, when read backwards, corresponds to that of the a(n)-th term of A074832.

1, 2, 3, 5, 4, 6, 8, 7, 9, 11, 10, 14, 15, 12, 13, 20, 23, 18, 21, 16, 19, 22, 17, 24, 31, 37, 32, 36, 30, 29, 25, 27, 35, 38, 33, 28, 26, 34, 39, 58, 49, 47, 56, 53, 45, 54, 42, 51, 41, 59, 48, 65, 44, 46, 63, 43, 57, 40, 50, 62, 64, 60, 55, 61, 52, 68, 93

Offset

1,2

Comments

This sequence is a self-inverse permutation of the positive integers.

Fixed points correspond to indices of terms of A016041 in A074832.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..11759

Rémy Sigrist, PARI program

Index entries for sequences that are permutations of the natural numbers

Formula

a(a(n)) = n.

A030101(A074832(n)) = A074832(a(n)).

Example

For n = 42: the binary expansion of A074832(42) = 277 is "100010101"; its reversal, "101010001", corresponds to 337 = A074832(47), so a(42) = 47.

Prog

(PARI) \\ See Links section.

Crossrefs

Cf. A016041, A030101, A074832, A143245, A388056 (decimal variant).

Sequence in context: A337136 A361314 A366474 * A380350 A138606 A166013

Adjacent sequences: A388052 A388053 A388054 * A388056 A388057 A388058

Keyword

nonn,base

Author

Rémy Sigrist, Sep 14 2025

Status

approved