A115306 a(n) = if n<6 then n else 6*a(floor(n/6)) + 5 - n mod 6.

1, 2, 3, 4, 5, 11, 10, 9, 8, 7, 6, 17, 16, 15, 14, 13, 12, 23, 22, 21, 20, 19, 18, 29, 28, 27, 26, 25, 24, 35, 34, 33, 32, 31, 30, 71, 70, 69, 68, 67, 66, 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 107

Offset: 1

Author

Reinhard Zumkeller, Jan 20 2006

Keywords

• nonn
• base
• easy

Comments

Self-inverse permutation of the natural numbers;

if n is written in base 6 representation, then a(n) is the value after replacing all digits d (but not the leading one) by 5-d.

Links

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

Crossrefs

Cf. A054429, A115303, A115304, A115305, A115307, A115308, A115309, A106649.

Programs

Mathematica

a[n_]:=If[n<6,n,6*a[Floor[n/6]]+5-Mod[n,6]];Table[a[n],{n,72}] (* James C. McMahon, Aug 11 2024 *)

Formula

a(n) = A115310(n+4, 5).