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A026595
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a(n) = T(n, floor(n/2)), where T is given by A026584.
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18
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1, 1, 1, 1, 5, 8, 19, 22, 69, 121, 341, 406, 1203, 2155, 6336, 7624, 22593, 40717, 121483, 147001, 438533, 792351, 2381512, 2892044, 8677763, 15703156, 47419503, 57728737, 173984792, 315180458, 954961034, 1164727748, 3522101709
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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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MATHEMATICA
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T[n_, k_]:= T[n, k]= If[k==0 || k==2*n, 1, If[k==1 || k==2*n-1, Floor[n/2], If[EvenQ[n+k], T[n-1, k-2] + T[n-1, k], T[n-1, k-2] + T[n-1, k-1] + T[n-1, k] ]]]; (* T = A026584 *)
Table[T[n, Floor[n/2]], {n, 0, 40}] (* G. C. Greubel, Dec 13 2021 *)
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PROG
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(Sage)
@CachedFunction
if (k==0 or k==2*n): return 1
elif (k==1 or k==2*n-1): return (n//2)
else: return T(n-1, k-2) + T(n-1, k) if ((n+k)%2==0) else T(n-1, k-2) + T(n-1, k-1) + T(n-1, k)
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CROSSREFS
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Cf. A026584, A026585, A026587, A026589, A026590, A026591, A026592, A026593, A026594, A026596, A026597, A026598, A026599, A027282, A027283, A027284, A027285, A027286.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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