A115307 - OEIS

A115307

a(n) = if n<7 then n else 7*a(floor(n/7)) + 6 - n mod 7.

1, 2, 3, 4, 5, 6, 13, 12, 11, 10, 9, 8, 7, 20, 19, 18, 17, 16, 15, 14, 27, 26, 25, 24, 23, 22, 21, 34, 33, 32, 31, 30, 29, 28, 41, 40, 39, 38, 37, 36, 35, 48, 47, 46, 45, 44, 43, 42, 97, 96, 95, 94, 93, 92, 91, 90, 89, 88, 87, 86, 85, 84, 83, 82, 81, 80, 79, 78, 77, 76, 75, 74

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OFFSET

1,2

COMMENTS

Self-inverse permutation of the natural numbers;

A115310(n+5,6) = a(n);

if n is written in base 7 representation, then a(n) is the value after replacing all digits d (but not the leading one) by 6-d.

LINKS

Table of n, a(n) for n=1..72.

Index entries for sequences that are permutations of the natural numbers

CROSSREFS

Cf. A054429, A115303, A115304, A115305, A115306, A115308, A115309, A106649.