A140263 Permutation of nonnegative integers obtained by interleaving A117967 and A117968.

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

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 A361329 A076555

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