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Search: id:A117454
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| A117454 |
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Triangle read by rows: T(n,k) is the number of partitions of n into distinct parts such that the difference between the largest and smallest parts is k (n>=1; 0<=k<=n-2 for n>=2). |
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2
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| 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 2, 0, 1, 1, 1, 0, 2, 0, 1, 1, 0, 1, 1, 2, 0, 1, 1, 1, 1, 1, 1, 2, 0, 1, 1, 0, 1, 2, 2, 1, 2, 0, 1, 1, 1, 0, 2, 2, 2, 1, 2, 0, 1, 1, 0, 2, 0, 3, 3, 2, 1, 2, 0, 1, 1, 1, 0, 2, 2, 3, 3, 2, 1, 2, 0, 1, 1, 0, 1, 2, 2, 3, 4, 3, 2, 1, 2, 0, 1, 1, 1, 1, 1, 3, 4, 3, 4, 3, 2, 1, 2, 0
(list; graph; listen)
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OFFSET
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1,14
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COMMENT
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Also number of partitions of n in which all integers smaller than the largest part occur and have k parts smaller than the largest part (n>=1, k>=0). Row 1 has one term; rows j (j>=2) have j-1 terms. Row sums yield A000009. sum(k*T(n,k),k=0..n-2)=A117455(n).
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FORMULA
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G.f.=G(t,x)=sum(t^(i-1)*x^(i(i+1)/2)/[(1-x^i)product(1-tx^j, j=1..i-1)], i=1..infinity).
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EXAMPLE
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T(12,5)=3 because we have [7,3,2],[6,5,1] and [6,3,2,1].
Triangle starts:
1;
1;
1,1;
1,0,1;
1,1,0,1;
1,0,2,0,1;
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MAPLE
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g:=sum(t^(i-1)*x^(i*(i+1)/2)/(1-x^i)/product(1-t*x^j, j=1..i-1), i=1..20): gser:=simplify(series(g, x=0, 20)): for n from 1 to 16 do P[n]:=coeff(gser, x^n) od: 1; for n from 2 to 16 do seq(coeff(P[n], t, j), j=0..n-2) od; # yields sequence in triangular form
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CROSSREFS
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Cf. A000009, A117455.
Sequence in context: A024363 A050600 A129691 this_sequence A115357 A063962 A084114
Adjacent sequences: A117451 A117452 A117453 this_sequence A117455 A117456 A117457
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KEYWORD
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nonn,tabf
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 18 2006
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