cp's OEIS Frontend

A192521 Monotonic ordering of set S generated by these rules: if x and y are in S then floor((x+1)(y+1)/2) is in S, and 2 is in S.

%I A192521 #5 Mar 30 2012 18:57:34
%S A192521 2,4,7,12,19,20,30,31,32,46,48,49,50,52,70,73,75,76,77,79,80,82,84,
%T A192521 106,111,114,115,117,120,121,122,124,125,127,128,130,132,136,160,168,
%U A192521 172,174,177,181,183,184,185,187,188,189,190,192,193,195,196,199,200
%N A192521 Monotonic ordering of set S generated by these rules:  if x and y are in S then floor((x+1)(y+1)/2) is in S, and 2 is in S.
%t A192521 start = {2}; f[x_, y_] := Floor[(x + 1)*(y + 1)/2]
%t A192521 b[x_] :=
%t A192521   Block[{w = x},
%t A192521    Select[Union[
%t A192521      Flatten[AppendTo[w,
%t A192521        Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
%t A192521       400 &]];
%t A192521 t = NestList[b, start, 14][[-1]] (* A192521 *)
%t A192521 Table[t[[i]] - t[[i - 1]], {i, 2, Length[t]}]  (* differences *)
%Y A192521 Cf. A192476.
%K A192521 nonn
%O A192521 1,1
%A A192521 _Clark Kimberling_, Jul 03 2011