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A115308
a(n) = if n<8 then n else 8*a(floor(n/8)) + 7 - n mod 8.
9
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.
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Jan 20 2006
STATUS
approved