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A076177
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a(n) = n!*sum_{ 0<=i<=j<=k<=n, i+j+k<=n } 1/(i!*j!*k!).
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2
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1, 2, 7, 31, 147, 801, 5028, 35757, 287703, 2594737, 25961688, 285620919, 3427588046, 44559016789, 623827340321, 9357413642355, 149718628050447, 2545216705948425, 45813900799435848, 870464115447489783, 17409282309719616078, 365594928506541029523, 8043088427150753393871
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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PROG
| (PARI) a(n)=n!*sum(i=0, n, sum(j=0, i, sum(k=0, j, (if(i+j+k-n, 0, 1)+if(sign(i+j+k-n)+1, 0, 1))/i!/j!/k!)))
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CROSSREFS
| Cf. A076176.
Sequence in context: A115605 A114198 A055836 * A007164 A126033 A007863
Adjacent sequences: A076174 A076175 A076176 * A076178 A076179 A076180
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 01 2002
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