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A092469
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a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (n+2j)!/(i! * (3j)! * k!).
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2
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1, 1, 13, 91, 1081, 10606, 181189, 2025325, 38378449, 548523856, 10811257051, 176339404099, 3828413138785, 68734868302738, 1590128353317001, 31543123841374681, 768191679788034529, 16494997547298477340
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OFFSET
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0,3
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LINKS
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PROG
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(PARI) a(n)=sum(i=0, n, sum(j=0, i, sum(k=0, j, if(i+j+k-n, 0, (n+2*j)!/i!/(2*j)!/k!))))
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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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