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A258257
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The number of representations of n as a minimal number of triangular numbers, A000217(n)
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6
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 3, 2, 2, 1, 2, 1, 2, 2, 1, 1, 1, 2, 5, 1, 2, 1, 2, 1, 1, 3, 1, 1, 2, 3, 1, 1, 1, 1, 2, 1, 1, 3, 2, 1, 2, 4, 2, 3, 1, 1, 2, 3, 6, 1, 1, 3, 3, 1
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OFFSET
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1,16
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LINKS
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EXAMPLE
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a(5) = 1 since 5 = 1 + 1 + 3 is the only representation as a minimal number of three triangular numbers.
a(16) = 2 since 16 = 1 + 15 = 6 + 10 has two representations as a minimal number of two triangular numbers.
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MATHEMATICA
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t[n_] := n (n + 1)/2; a[n_] := Block[{k = 1, t, tt = t /@ Range[ Sqrt[2*n]]}, While[{} == (r = IntegerPartitions[n, {k}, tt]), k++]; Length@r]; Array[a, 100] (* Giovanni Resta, Jun 09 2015 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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