A140264 Inverse permutation to A140263.

0, 1, 2, 5, 7, 3, 6, 4, 8, 17, 19, 15, 23, 25, 21, 11, 13, 9, 18, 16, 20, 12, 10, 14, 24, 22, 26, 53, 55, 51, 59, 61, 57, 47, 49, 45, 71, 73, 69, 77, 79, 75, 65, 67, 63, 35, 37, 33, 41, 43, 39, 29, 31, 27, 54, 52, 56, 48, 46, 50, 60, 58, 62, 36, 34, 38, 30, 28, 32, 42, 40, 44

Offset: 0

Author

Antti Karttunen, May 19 2008

Keywords

• nonn

Links

• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Inverse: A140263.

Programs

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 a140266(n): return Z(a117966(n - 1))
def a(n): return a140266(n + 1) - 1 # Indranil Ghosh, Jun 07 2017

Scheme

(define (A140264 n) (- (A140266 (+ 1 n)) 1))

Formula

a(n) = A140266(n+1)-1.