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A026548 a(n) = T(n,0) + T(n,1) + ... + T(n,n), T given by A026536. 3
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
0,3
LINKS
FORMULA
a(n) = Sum_{k=0..n} A026536(n, k).
MATHEMATICA
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 *)
PROG
(SageMath)
@CachedFunction
def T(n, k): # A026536
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))
[A026548(n) for n in (0..40)] # G. C. Greubel, Apr 12 2022
CROSSREFS
Sequence in context: A119561 A228015 A145931 * A100098 A127361 A128533
KEYWORD
nonn
AUTHOR
EXTENSIONS
Missing a(0)=1 inserted by Sean A. Irvine, Oct 06 2019
STATUS
approved

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Last modified September 18 23:40 EDT 2024. Contains 376002 sequences. (Running on oeis4.)