OFFSET
1,1
MATHEMATICA
start = {2}; f[x_, y_] := Floor[(x + 1)*(y + 1)/2]
b[x_] :=
Block[{w = x},
Select[Union[
Flatten[AppendTo[w,
Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
400 &]];
t = NestList[b, start, 14][[-1]] (* A192521 *)
Table[t[[i]] - t[[i - 1]], {i, 2, Length[t]}] (* differences *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jul 03 2011
STATUS
approved