0,1

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)= -5 + Sum_{k=0..n}{(1/36)*(-47*(k mod 9)-11*((k+1) mod 9)+25*((k+2) mod 9)-11*((k+3) mod 9)-11*((k+4) mod 9)-11*((k+5) mod 9)+25*((k+6) mod 9)-11*((k+7) mod 9)+61*((k+8) mod 9)},with n>=0 - Paolo P. Lava (ppl(AT)spl.at), Dec 03 2007

Sequence in context: A154499 A092750 A153791 this_sequence A091899 A104175 A019792

Adjacent sequences: A004494 A004495 A004496 this_sequence A004498 A004499 A004500

nonn

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