

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
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OFFSET

1,1


LINKS

Clark Kimberling, Table of n, a(n) for n = 1..10000


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

Cf. A160009, A274280, A274432.
Sequence in context: A278580 A028929 A308299 * A018731 A232966 A113961
Adjacent sequences: A274449 A274450 A274451 * A274453 A274454 A274455


KEYWORD

nonn,easy


AUTHOR

Clark Kimberling, Jun 23 2016


STATUS

approved



