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A274452
Products of distinct Narayana's cow numbers (A000930).
2
2, 3, 4, 6, 8, 9, 12, 13, 18, 19, 24, 26, 27, 28, 36, 38, 39, 41, 48, 52, 54, 56, 57, 60, 72, 76, 78, 82, 84, 88, 104, 108, 112, 114, 117, 120, 123, 129, 144, 152, 156, 162, 164, 168, 171, 176, 180, 189, 216, 224, 228, 234, 240, 246, 247, 252, 258, 264, 277
OFFSET
1,1
LINKS
EXAMPLE
The Narayana's cow numbers numbers are 1, 2, 3, 4, 6, 9, 13, 19, 28, ..., so that the sequence of all products of distinct members, in increasing order, is (2, 3, 4, 6, 8, 9, 12, 13, 18, 19, 24, ...).
MATHEMATICA
r[1] := 1; r[2] := 1; r[3] = 1; r[n_] := r[n] = r[n - 1] + r[n - 3]
s = {1}; z = 60; f = Map[r, Range[z]]; Take[f, 20] (*A000930*)
Do[s = Union[s, Select[s*f[[i]], # <= f[[z]] &]], {i, z}];
Take[s, 2 z] (* A274452 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 23 2016
STATUS
approved