This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A163241 Simple self-inverse permutation: Write n in base 4, then replace each digit '2' with '3' and vice versa, then convert back to decimal. 9
 0, 1, 3, 2, 4, 5, 7, 6, 12, 13, 15, 14, 8, 9, 11, 10, 16, 17, 19, 18, 20, 21, 23, 22, 28, 29, 31, 30, 24, 25, 27, 26, 48, 49, 51, 50, 52, 53, 55, 54, 60, 61, 63, 62, 56, 57, 59, 58, 32, 33, 35, 34, 36, 37, 39, 38, 44, 45, 47, 46, 40, 41, 43, 42, 64, 65, 67, 66, 68, 69, 71, 70 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS A. Karttunen, Table of n, a(n) for n = 0..1023 FORMULA a(n) = A000695(A003987bi(A059905(n),A059906(n))) + 2*A000695(A059906(n)), where A003987bi is binary XOR. EXAMPLE 43 in quaternary base (A007090) is written as '223' (2*16 + 2*4 + 3), which is then mapped to '332' = 3*16 + 3*4 + 2 = 62, thus a(43) = 62, and likewise a(62) = 43. MATHEMATICA Table[FromDigits[IntegerDigits[n, 4]/.{2->a, 3->b}/.{a->3, b->2}, 4], {n, 0, 75}] (* Harvey P. Dale, Nov 29 2011 *) PROG (Scheme) (define (A163241 n) (+ (A000695 (A003987bi (A059905 n) (A059906 n))) (* 2 (A000695 (A059906 n))))) (Python) def a000695(n):     n=bin(n)[2:]     x=len(n)     return sum([int(n[i])*4**(x - 1 - i) for i in xrange(x)]) def a059905(n): return sum([(n>>2*i&1)<

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.