0,2

Could also be described as "Write n in base 3, then replace each digit by its base 3 negative" as with A048647 for base 4 - Henry Bottomley (se16(AT)btinternet.com), Apr 19 2000

a(a(n)) = n, a self-inverse permutation of natural numbers. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 19 2003

Index entries for sequences that are permutations of the natural numbers

Tersum m + n: write m and n in base 3 and add mod 3 with no carries, e.g. 5 + 8 = "21" + "22" = "10" = 1.

a(n) = Sum(3-d(i)-3*0^d(i): n=Sum(d(i)*3^d(i): 0<=d(i)<3)); - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 19 2003

Sequence in context: A026220 A138750 A048850 this_sequence A011419 A011133 A073675

Adjacent sequences: A004485 A004486 A004487 this_sequence A004489 A004490 A004491

nonn

N. J. A. Sloane (njas(AT)research.att.com).