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A308296
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a(n) = (1/n!) * Sum_{i_1=1..n} Sum_{i_2=1..n} ... Sum_{i_n=1..n} multinomial(i_1+i_2+...+i_n; i_1, i_2, ... , i_n).
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4
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1, 1, 7, 842, 7958726, 15467641899285, 10893033763705794846727, 4247805448772073978048752721163278, 1299618941291522676629215597535104557826094801396, 419715170056359079715862408734598208208707081189266290220651371206
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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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EXAMPLE
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a(2) = (1/2) * (binomial(1+1,1) + binomial(1+2,2) + binomial(2+1,1) + binomial(2+2,2)) = 7.
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PROG
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(PARI) {a(n) = sum(i=n, n^2, i!*polcoef(sum(j=1, n, x^j/j!)^n, i))/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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