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A065567
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T(n,m) is the sum over all m-subsets of {1,..,n} of the GCD of the subset.
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2
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1, 3, 1, 6, 3, 1, 10, 7, 4, 1, 15, 11, 10, 5, 1, 21, 20, 21, 15, 6, 1, 28, 26, 36, 35, 21, 7, 1, 36, 38, 60, 71, 56, 28, 8, 1, 45, 50, 90, 127, 126, 84, 36, 9, 1, 55, 67, 132, 215, 253, 210, 120, 45, 10, 1, 66, 77, 177, 335, 463, 462, 330, 165, 55, 11, 1, 78, 105, 250, 512
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| First differences of row sums equals A034738.
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EXAMPLE
| 1; 3,1; 6,3,1; 10,7,4,1; 15,11,10,5,1; ...
T(4,2)=7 since GCD[1,2] + GCD[1,3] + GCD[1,4] + GCD[2,3] + GCD[2,4] + GCD[3,4] = 7.
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MAPLE
| with(combstruct):
a065567_row := proc(n) local k, L, l, R, comb;
R := NULL;
for k from 1 to n do
L := 0;
comb := iterstructs(Combination(n), size=k):
while not finished(comb) do
l := nextstruct(comb);
L := L + igcd(op(l));
od;
R := R, L;
od;
R end: - Peter Luschny, Dec 07 2010
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MATHEMATICA
| Table[Plus@@(GCD@@@KSubsets[Range[n], m]), {n, 16}, {m, n}]
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CROSSREFS
| Cf. A065568, A034738.
Sequence in context: A122432 A131110 A133093 * A100861 A131031 A130452
Adjacent sequences: A065564 A065565 A065566 * A065568 A065569 A065570
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KEYWORD
| nonn,tabl
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AUTHOR
| Wouter Meeussen (wouter.meeussen(AT)pandora.be), Nov 30 2001
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