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A133138
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Triangle T(n,k) of the coefficients of the polynomials Q(n,x)=(1+x)[(1+x)^(n-1)+x^(n-1)], Q(0,x)=2.
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3
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2, 2, 2, 1, 3, 2, 1, 3, 4, 2, 1, 4, 6, 5, 2, 1, 5, 10, 10, 6, 2, 1, 6, 15, 20, 15, 7, 2, 1, 7, 21, 35, 35, 21, 8, 2, 1, 8, 28, 56, 70, 56, 28, 9, 2, 1, 9, 36, 84, 126, 126, 84, 36, 10, 2, 1, 10, 45, 120, 210, 252, 210, 120, 45, 11, 2
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OFFSET
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0,1
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LINKS
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FORMULA
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T(n,k) = A007318(n,k), 0 <= k < n-1.
T(n,k) = A007318(n,k)+1, n-1 <= k <= n.
Sum_{k=0..n} T(n,k) = A133140(n). (End)
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EXAMPLE
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Triangle T(n,k) begins:
n/k 0 1 2 3 4 5 6 7 8 9 10 11 12
0: 2
1: 2 2
2: 1 3 2
3: 1 3 4 2
4: 1 4 6 5 2
5: 1 5 10 10 6 2
6: 1 6 15 20 15 7 2
7: 1 7 21 35 35 21 8 2
8: 1 8 28 56 70 56 28 9 2
9: 1 9 36 84 126 126 84 36 10 2
10: 1 10 45 120 210 252 210 120 45 11 2
11: 1 11 55 165 330 462 462 330 165 55 12 2
12: 1 12 66 220 495 792 924 792 495 220 66 13 2
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MATHEMATICA
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q[n_] := (1+x)*((1+x)^(n-1) + x^(n-1)); t[n_, k_] := Coefficient[q[n], x, k]; Table[t[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Dec 16 2013 *)
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PROG
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(Maxima)
Q(n, x) := (1 + x)*((1 + x)^(n - 1) + x^(n - 1))$
t(n, k) := ratcoef(expand(Q(n, x)), x, k)$
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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