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

Author

Reinhard Zumkeller, Jan 20 2006

Keywords

• nonn
• base

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

• Index entries for sequences that are permutations of the natural numbers

Crossrefs

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

Formula

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