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Search: id:A081064
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| A081064 |
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Number of labeled acyclic digraphs with n nodes and k arcs. |
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+0
3
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| 1, 1, 2, 1, 6, 12, 6, 1, 12, 60, 152, 186, 108, 24, 1, 20, 180, 940, 3050, 6180, 7960, 6540, 3330, 960, 120, 1, 30, 420, 3600, 20790, 83952, 240480, 496680, 750810, 838130, 691020, 416160, 178230, 51480, 9000, 720, 1, 42, 840, 10570, 93030, 601944
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Row sums give A003024.
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FORMULA
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1 = 1*exp(-x)+1*exp(-(1+y)*x)*x/1!+(2*y+1)*exp(-(1+y)^2*x)*x^2/2!+(6*y^3+12*y^2+6*y+1)*exp(-(1+y)^3*x)*x^3/3!+ (24*y^6+108*y^5+186*y^4+152*y^3+60*y^2+12*y+1)*exp(-(1+y)^4*x)*x^4/4!+(120*y^10+960*y^9+3330*y^8+6540*y^7+7960*y^6+6180*y^5+3050*y^4+940*y^3+180*y^2+20*y+1)*exp(-(1+y)^5*x)*x^5/5!+... - Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 07 2005
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EXAMPLE
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1; 1,2; 1,6,12,6; 1,12,60,152,186,108,24; ...
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CROSSREFS
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Sequence in context: A106192 A113025 A113216 this_sequence A128534 A002562 A136456
Adjacent sequences: A081061 A081062 A081063 this_sequence A081065 A081066 A081067
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KEYWORD
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easy,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 15 2003
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