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A064429
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a(n) = floor(n / 3) * 3 + signum(n mod 3) * (3 - n mod 3).
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7
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0, 2, 1, 3, 5, 4, 6, 8, 7, 9, 11, 10, 12, 14, 13, 15, 17, 16, 18, 20, 19, 21, 23, 22, 24, 26, 25, 27, 29, 28, 30, 32, 31, 33, 35, 34, 36, 38, 37, 39, 41, 40, 42, 44, 43, 45, 47, 46, 48, 50, 49, 51, 53, 52, 54, 56, 55, 57, 59, 58, 60, 62, 61, 63, 65, 64, 66, 68, 67, 69, 71, 70
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| a(a(n)) = n (a self-inverse permutation).
Take natural numbers, exchange trisections starting with 1 and 2.
Lodumo_3 of A080425 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Apr 26 2009]
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LINKS
| Eric Weisstein's World of Mathematics, Alternating Permutations
Index entries for sequences that are permutations of the natural numbers
Index to sequences with linear recurrences with constant coefficients, signature (1,0,1,-1)
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FORMULA
| a(n) = A080782(n+1) - 1.
a(n) = n - 2*sin(4*pi*n/3)/sqrt(3) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Dec 05 2008]
a(n)=lod_3(A080425(n)). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Apr 26 2009]
G.f. x*(2-x+2*x^2) / ( (1+x+x^2)*(x-1)^2 ). - R. J. Mathar, Feb 20 2011
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CROSSREFS
| Cf. A004442, A074066.
Equals A001477+A102283 [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Dec 05 2008]
Sequence in context: A182939 A056943 A171085 * A113790 A181094 A181560
Adjacent sequences: A064426 A064427 A064428 * A064430 A064431 A064432
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 15 2001
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