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A352972
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a(n) = Sum_{j=0..2*n} Sum_{k=0..j} A026536(j, k).
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2
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1, 6, 35, 204, 1199, 7089, 42070, 250269, 1491262, 8896310, 53118352, 317373194, 1897253203, 11346582851, 67882263130, 406231442387, 2431626954934, 14558306758418, 87177151134954, 522110098886882, 3127380060424476, 18734897945679836, 112245303177542790, 672552484035697364, 4030148584900522009
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = Sum_{j=0..2*n} Sum_{k=0..j} A026536(j, k).
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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]] ]];
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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 A352972(n): return sum(sum(T(j, k) for k in (0..j)) for j in (0..2*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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STATUS
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approved
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