%I #7 Oct 26 2023 23:11:01
%S 23,21,22,26,24,25,20,18,19,5,3,4,8,6,7,2,0,1,14,12,13,17,15,16,11,9,
%T 10,50,48,49,53,51,52,47,45,46,32,30,31,35,33,34,29,27,28,41,39,40,44,
%U 42,43,38,36,37,77,75,76,80
%N Tersum n + 23.
%F 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.
%K nonn
%O 0,1
%A _N. J. A. Sloane_