OFFSET
1,2
EXAMPLE
MATHEMATICA
mex:=First[Complement[Range[1, Max[#1]+1], #1]]&;
s[n_]:=Floor[(n+2)/3]; a[1]=1; b[n_]:=b[n]=s[n]+a[n];
a[n_]:=a[n]=mex[Flatten[Table[{a[i], b[i]}, {i, 1, n-1}]]];
Table[s[n], {n, 20}]
Table[a[n], {n, 100}]
Table[b[n], {n, 100}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 13 2011
STATUS
approved