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A242618
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Number T(n,k) of partitions of n, where k is the difference between the number of odd parts and the number of even parts, both counted without multiplicity; triangle T(n,k), n>=0, read by rows.
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28
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1, 1, 1, 0, 1, 1, 2, 2, 1, 1, 1, 4, 2, 1, 1, 2, 3, 3, 2, 1, 8, 3, 3, 2, 4, 6, 5, 5, 4, 13, 8, 4, 1, 5, 5, 11, 13, 7, 1, 11, 20, 14, 9, 2, 1, 6, 13, 17, 26, 11, 3, 1, 22, 31, 27, 15, 5, 2, 12, 18, 34, 44, 18, 7, 4, 40, 47, 51, 23, 11, 5, 16, 36, 56, 72, 34, 11, 1
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OFFSET
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0,7
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COMMENTS
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T(n^2,n) = T(n^2+n,-n) = 1.
T(n^2+n,n) = Sum_{k} T(n,k) = A000041(n).
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LINKS
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EXAMPLE
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Triangle T(n,k) begins:
: n\k : -3 -2 -1 0 1 2 3 ...
+-----+---------------------------
: 0 : 1;
: 1 : 1;
: 2 : 1, 0, 1;
: 3 : 1, 2;
: 4 : 2, 1, 1, 1;
: 5 : 4, 2, 1;
: 6 : 1, 2, 3, 3, 2;
: 7 : 1, 8, 3, 3;
: 8 : 2, 4, 6, 5, 5;
: 9 : 4, 13, 8, 4, 1;
: 10 : 5, 5, 11, 13, 7, 1;
: 11 : 11, 20, 14, 9, 2;
: 12 : 1, 6, 13, 17, 26, 11, 3;
: 13 : 1, 22, 31, 27, 15, 5;
: 14 : 2, 12, 18, 34, 44, 18, 7;
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MAPLE
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b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
expand(b(n, i-1)+add(b(n-i*j, i-1)*x^(2*irem(i, 2)-1), j=1..n/i))))
end:
T:= n-> (p-> seq(coeff(p, x, i), i=ldegree(p)..degree(p)))(b(n$2)):
seq(T(n), n=0..20);
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MATHEMATICA
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b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, Expand[b[n, i - 1] + Sum[b[n - i*j, i - 1]*x^(2*Mod[i, 2] - 1), {j, 1, n/i}]]]]; T[n_] := Function[p, Table[Coefficient[p, x, i], {i, Exponent[p, x, Min], Exponent[p, x]}]][b[n, n]]; Table[T[n], {n, 0, 20}] // Flatten (* Jean-François Alcover, Dec 12 2016 after Alois P. Heinz *)
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CROSSREFS
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Columns k=(-10)-10 give: A242682, A242683, A242684, A242685, A242686, A242687, A242688, A242689, A242690, A242691, A241638, A242692, A242693, A242694, A242695, A242696, A242697, A242698, A242699, A242700, A242701.
Cf. A240009 (parts counted with multiplicity), A240021 (distinct parts), A242626 (compositions counted without multiplicity).
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KEYWORD
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AUTHOR
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STATUS
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approved
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