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A179661
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Triangle read by rows: T(n,k) is the largest least common multiple of any k-element subset of the first n positive integers.
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3
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1, 2, 2, 3, 6, 6, 4, 12, 12, 12, 5, 20, 60, 60, 60, 6, 30, 60, 60, 60, 60, 7, 42, 210, 420, 420, 420, 420, 8, 56, 280, 840, 840, 840, 840, 840, 9, 72, 504, 2520, 2520, 2520, 2520, 2520, 2520, 10, 90, 630, 2520, 2520, 2520, 2520, 2520, 2520, 2520, 11, 110, 990
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OFFSET
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1,2
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COMMENTS
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Sequence differs from A093919; first divergences are at indices 31, 40, 48, 59.
Main diagonal is A003418.
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LINKS
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Table of n, a(n) for n=1..58.
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FORMULA
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T(n,k) = max{ lcm(x_1,...,x_k) ; 0 < x_1 < ... < x_k <= n }.
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EXAMPLE
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Triangle begins:
[ 1 ],
[ 2, 2 ],
[ 3, 6, 6 ],
[ 4, 12, 12, 12 ],
[ 5, 20, 60, 60, 60 ],
[ 6, 30, 60, 60, 60, 60 ].
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MATHEMATICA
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A179661[n_, k_]:=Max[LCM@@@Subsets[Range[n], {k}]];
A002260[n_]:=n-Binomial[Floor[1/2+Sqrt[2*n]], 2];
A002024[n_]:=Floor[1/2+Sqrt[2*n]];
A179661[n_]:=A179661[A002024[n], A002260[n]]
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PROG
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(MAGMA) A179661:=func< n, k | Max([ LCM(s): s in Subsets({1..n}, k) ]) >; z:=12; [ A179661(n, k): k in [1..n], n in [1..z] ]; - Klaus Brockhaus, Jan 16 2011
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CROSSREFS
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Cf. A093919, A096179, A003418.
Sequence in context: A070871 A096115 A093919 * A178888 A068424 A139359
Adjacent sequences: A179658 A179659 A179660 * A179662 A179663 A179664
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KEYWORD
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nonn,tabl
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AUTHOR
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Enrique Pérez Herrero, Jan 09 2011
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STATUS
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approved
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