a(n) = { my (v=0, t=Vecrev(digits(n, 3))); for (k=1, #t, if (t[k]==1, v=+3^(k-1)-v, t[k]==2, v=-3^(k-1)-v)); v } plus = vector(rem=3^logint(10 000, 3)) minus = vector(rem) { for (n=1, oo, w=abs(v=a(n)); if (w<=#plus, if (v>0, plus[w]=n, minus[w]=n); if (plus[w] && minus[w], if (rem--==0, break; ); ); ); ); print ("0 0"); for (n=1, #plus, print (n " " minus[n]-plus[n]); ); } quit