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A157272
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Triangle T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k+1 if k <= floor(n/2) otherwise 2*(n-k)+1, and m = 1, read by rows.
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23
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1, 1, 1, 1, 7, 1, 1, 20, 20, 1, 1, 47, 155, 47, 1, 1, 102, 753, 753, 102, 1, 1, 213, 3004, 7109, 3004, 213, 1, 1, 436, 10800, 48727, 48727, 10800, 436, 1, 1, 883, 36517, 280736, 551251, 280736, 36517, 883, 1, 1, 1778, 118795, 1454163, 4879214, 4879214, 1454163, 118795, 1778, 1
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OFFSET
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0,5
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LINKS
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FORMULA
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T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k+1 if k <= floor(n/2) otherwise 2*(n-k)+1, and m = 1.
T(n, n-k, m) = T(n, k, m).
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EXAMPLE
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Triangle begins as:
1;
1, 1;
1, 7, 1;
1, 20, 20, 1;
1, 47, 155, 47, 1;
1, 102, 753, 753, 102, 1;
1, 213, 3004, 7109, 3004, 213, 1;
1, 436, 10800, 48727, 48727, 10800, 436, 1;
1, 883, 36517, 280736, 551251, 280736, 36517, 883, 1;
1, 1778, 118795, 1454163, 4879214, 4879214, 1454163, 118795, 1778, 1;
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MATHEMATICA
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f[n_, k_]:= If[k<=Floor[n/2], 2*k+1, 2*(n-k)+1];
T[n_, k_, m_]:= T[n, k, m]= If[k==0 || k==n, 1, (m*(n-k)+1)*T[n-1, k-1, m] + (m*k+1)*T[n-1, k, m] + m*f[n, k]*T[n-2, k-1, m]];
Table[T[n, k, 1], {n, 0, 12}, {k, 0, n}]//Flatten (* modified by G. C. Greubel, Feb 04 2022 *)
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PROG
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(Sage)
def f(n, k): return 2*k+1 if (k <= n//2) else 2*(n-k)+1
@CachedFunction
if (k==0 or k==n): return 1
else: return (m*(n-k) +1)*T(n-1, k-1, m) + (m*k+1)*T(n-1, k, m) + m*f(n, k)*T(n-2, k-1, m)
flatten([[T(n, k, 1) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Feb 04 2022
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CROSSREFS
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Cf. A157147, A157148, A157149, A157150, A157151, A157152, A157153, A157154, A157155, A157156, A157207, A157208, A157209, A157210, A157211, A157212, A157268, A157275, A157277, A157278.
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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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