A115308 a(n) = if n<8 then n else 8*a(floor(n/8)) + 7 - n mod 8.

1, 2, 3, 4, 5, 6, 7, 15, 14, 13, 12, 11, 10, 9, 8, 23, 22, 21, 20, 19, 18, 17, 16, 31, 30, 29, 28, 27, 26, 25, 24, 39, 38, 37, 36, 35, 34, 33, 32, 47, 46, 45, 44, 43, 42, 41, 40, 55, 54, 53, 52, 51, 50, 49, 48, 63, 62, 61, 60, 59, 58, 57, 56, 127, 126, 125, 124, 123, 122, 121

Offset

1,2

Comments

Self-inverse permutation of the natural numbers;

A115310(n+6,7) = a(n);

if n is written in octal representation, then a(n) is the value after replacing all digits d (but not the leading one) by 7-d.

Links

Table of n, a(n) for n=1..70.

Index entries for sequences that are permutations of the natural numbers

Formula

a(n) = n XOR (8^floor(log_8(n)) - 1). - Alan Michael Gómez Calderón, Mar 27 2025

Crossrefs

Cf. A054429, A115303, A115304, A115305, A115306, A115307, A115309, A106649.

Sequence in context: A032996 A032942 A273734 * A171649 A146028 A263469

Adjacent sequences: A115305 A115306 A115307 * A115309 A115310 A115311

Keyword

nonn,base

Author

Reinhard Zumkeller, Jan 20 2006

Status

approved