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A115309
a(n) = if n<9 then n else 9*a(floor(n/9)) + 8 - n mod 9.
9
1, 2, 3, 4, 5, 6, 7, 8, 17, 16, 15, 14, 13, 12, 11, 10, 9, 26, 25, 24, 23, 22, 21, 20, 19, 18, 35, 34, 33, 32, 31, 30, 29, 28, 27, 44, 43, 42, 41, 40, 39, 38, 37, 36, 53, 52, 51, 50, 49, 48, 47, 46, 45, 62, 61, 60, 59, 58, 57, 56, 55, 54, 71, 70, 69, 68, 67, 66, 65, 64, 63, 80
OFFSET
1,2
COMMENTS
Self-inverse permutation of the natural numbers;
A115310(n+7,8) = a(n);
if n is written in base 9 representation, then a(n) is the value after replacing all digits d (but not the leading one) by 8-d.
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Jan 20 2006
STATUS
approved