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A140266 Inverse permutation to A140265. 3
1, 2, 3, 6, 8, 4, 7, 5, 9, 18, 20, 16, 24, 26, 22, 12, 14, 10, 19, 17, 21, 13, 11, 15, 25, 23, 27, 54, 56, 52, 60, 62, 58, 48, 50, 46, 72, 74, 70, 78, 80, 76, 66, 68, 64, 36, 38, 34, 42, 44, 40, 30, 32, 28, 55, 53, 57, 49, 47, 51, 61, 59, 63, 37, 35, 39, 31, 29, 33, 43, 41, 45 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

A. Karttunen, Table of n, a(n) for n = 1..729

Index entries for sequences that are permutations of the natural numbers

FORMULA

a(n) = Z->N(A117966(n-1)), where Z->N(z) = 2z if z>0 else 2|z|+1.

PROG

(Scheme:) (string-append (define (A140266 n) (Z->N (A117966 (- n 1))))

(define (Z->N n) (if (positive? n) (* n 2) (+ 1 (* 2 (- n))))))

(Python)

def a117966(n):

    if n==0: return 0

    if n%3==0: return 3*a117966(n/3)

    elif n%3==1: return 3*a117966((n - 1)/3) + 1

    else: return 3*a117966((n - 2)/3) - 1

def Z(z): return 2*z if z>0 else 2*abs(z) + 1

def a(n): return Z(a117966(n - 1)) # Indranil Ghosh, Jun 07 2017

CROSSREFS

Inverse: A140265. a(n) = A140264(n-1)+1.

Sequence in context: A133441 A086254 A265297 * A140265 A191453 A191454

Adjacent sequences:  A140263 A140264 A140265 * A140267 A140268 A140269

KEYWORD

nonn,look,hear

AUTHOR

Antti Karttunen, May 19 2008

STATUS

approved

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Last modified November 16 03:09 EST 2018. Contains 317252 sequences. (Running on oeis4.)