

A181099


Exchange rightmost two ternary digits of n > 1; a(0)=0, a(1)=3.


0



0, 3, 6, 1, 4, 7, 2, 5, 8, 9, 12, 15, 10, 13, 16, 11, 14, 17, 18, 21, 24, 19, 22, 25, 20, 23, 26, 27, 30, 33, 28, 31, 34, 29, 32, 35, 36, 39, 42, 37, 40, 43, 38, 41, 44, 45, 48, 51, 46, 49, 52, 47, 50, 53, 54, 57, 60, 55, 58, 61, 56, 59, 62, 63, 66, 69, 64, 67, 70, 65, 68, 71, 72
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OFFSET

0,2


COMMENTS

Selfinverse permutation of natural numbers: a(a(n)) = n.


LINKS

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,1,1).


FORMULA

a(n) = a(n1) + a(n9)  a(n10) = 9 *floor(n/9) + 3*(n mod 3) + (floor(n/3) mod 3).
G.f.: x*(3 + 3*x  5*x^2 + 3*x^3 + 3*x^4  5*x^5 + 3*x^6 + 3*x^7 + x^8) / ( (1+x+x^2)*(x^6+x^3+1)*(x1)^2 ). (End)


EXAMPLE

a(10) = a(101_3) = 110_3 = 12.
a(20) = a(202_3) = 220_3 = 24.
a(30) = a(1010_3) = 1001_3 = 28.


CROSSREFS



KEYWORD

base,easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



