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A154425
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a(n) = A142458(n, 1 + floor(n/2)).
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1
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1, 1, 8, 39, 546, 5482, 109640, 1709675, 44451550, 947113254, 30307624128, 821539580358, 31218504053604, 1028949571999572, 45273781167981168, 1758747856988046771, 87937392849402338550, 3935893923685215214030
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listen;
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internal format)
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OFFSET
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1,3
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LINKS
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FORMULA
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MATHEMATICA
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T[n_, k_, m_]:= T[n, k, m]= If[k==1 || k==n, 1, (m*n-m*k+1)*T[n-1, k-1, m] + (m*k-m+1)*T[n-1, k, m]];
A154425[n_]:= T[n, 1+Floor[n/2], 3];
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PROG
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(Sage)
@CachedFunction
if (k==1 or k==n): return 1
else: return (m*(n-k)+1)*T(n-1, k-1, m) + (m*k-m+1)*T(n-1, k, m)
def A154425(n): return T(n, 1 + (n//2), 3)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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