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A122486
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a(n) = Sum_{k=0..n} |Stirling1(n,k)|*Bell(k)^2.
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0
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1, 1, 5, 39, 425, 6053, 107735, 2321469, 59152987, 1750362419, 59286010621, 2271617296347, 97502863649141, 4649359584613201, 244550369307356039, 14101227268075911837, 886551391533830227267, 60482082002935189216499
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(n) = exp(-2)*Sum_{r,s>=0} [r*s]^n/(r!*s!), where [m]^n = m*(m+1)*...*(m+n-1) is the rising factorial.
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MAPLE
| with(combinat): seq(sum(abs(stirling1(n, k))*bell(k)^2, k=0..n), n=0..19); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Oct 08 2006
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CROSSREFS
| Cf. A000110, A059849.
Sequence in context: A024216 A127189 A121354 * A199244 A193118 A118991
Adjacent sequences: A122483 A122484 A122485 * A122487 A122488 A122489
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 15 2006, Sep 19 2006
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EXTENSIONS
| More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Oct 08 2006
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