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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 18 14:37 EST 2019. Contains 329262 sequences. (Running on oeis4.)