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A026548
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a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A026536.
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3
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1, 1, 4, 7, 22, 42, 127, 249, 746, 1476, 4414, 8766, 26215, 52158, 156041, 310799, 930194, 1854072, 5550976, 11070000, 33152042, 66139316, 198115526, 395368914, 1184511095, 2364457980, 7084871668, 14145343660, 42390336619
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OFFSET
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0,3
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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], T[n-1, k-2] +T[n-1, k-1] +T[n-1, k], T[n-1, k-2] +T[n-1, k]]]];
Table[Sum[T[n, k], {k, 0, n}], {n, 0, 40}] (* G. C. Greubel, Apr 12 2022 *)
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PROG
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(SageMath)
@CachedFunction
if k == 0 or k == 2*n: return 1
elif k == 1 or k == 2*n-1: return n//2
elif n % 2 == 1: return T(n-1, k-2) + T(n-1, k)
return T(n-1, k-2) + T(n-1, k-1) + T(n-1, k)
def A026548(n): return sum(T(n, k) for k in (0..n))
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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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