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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = Sum_{k=0..n} T(n, k) where T(n, k) = T(n-1, k-1)^2 + T(n-1, k)^2; T(0,0)=1; T(n,-1):=0; T(n, k):=0, n < k.
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EXAMPLE
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1 = 1;
1 + 1 = 2;
1 + 2 + 1 = 4;
1 + 5 + 5 + 1 = 12.
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PROG
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(Python)
def r(i):
t = [[0, 1, 0], [0, 1, 1, 0]]
for n in range(2, i+1):
t.append([0])
for k in range(1, n+2):
t[n].append(t[n-1][k-1]**2 + t[n-1][k]**2)
t[n].append(0)
return(sum(t[i]))
for n in range(1, 10):
print (r(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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