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A140263 Permutation of nonnegative integers obtained by interleaving A117967 and A117968. 8
0, 1, 2, 5, 7, 3, 6, 4, 8, 17, 22, 15, 21, 16, 23, 11, 19, 9, 18, 10, 20, 14, 25, 12, 24, 13, 26, 53, 67, 51, 66, 52, 68, 47, 64, 45, 63, 46, 65, 50, 70, 48, 69, 49, 71, 35, 58, 33, 57, 34, 59, 29, 55, 27, 54, 28, 56, 32, 61, 30, 60, 31, 62, 44, 76, 42, 75, 43, 77, 38, 73, 36 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

A. Karttunen, Table of n, a(n) for n = 0..2186

Index entries for sequences that are permutations of the natural numbers

FORMULA

a(n) = A117967(A001057(n)). (Assuming that the domain of A117967 is the whole Z line.)

PROG

(Python)

from sympy import ceiling

from sympy.ntheory.factor_ import digits

def a004488(n): return int("".join([str((3 - i)%3) for i in digits(n, 3)[1:]]), 3)

def a117968(n):

    if n==1: return 2

    if n%3==0: return 3*a117968(n/3)

    elif n%3==1: return 3*a117968((n - 1)/3) + 2

    else: return 3*a117968((n + 1)/3) + 1

def a117967(n): return 0 if n==0 else a117968(-n) if n<0 else a004488(a117968(n))

def a001057(n): return -(-1)**n*ceiling(n/2)

def a(n): return a117967(a001057(n)) # Indranil Ghosh, Jun 07 2017

CROSSREFS

Inverse: A140264. Bisections: A117967 & A117968. a(n) = A140265(n+1)-1.

Cf. A004488, A117966.

Sequence in context: A133133 A024710 A140264 * A073929 A076555 A095928

Adjacent sequences:  A140260 A140261 A140262 * A140264 A140265 A140266

KEYWORD

nonn,look,hear

AUTHOR

Antti Karttunen, May 19 2008, originally described in a posting at the SeqFan mailing list on Sep 15 2005.

STATUS

approved

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Last modified November 13 10:55 EST 2018. Contains 317133 sequences. (Running on oeis4.)