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A274872
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Number of set partitions of [n] into exactly eight blocks such that all odd elements are in blocks with an odd index and all even elements are in blocks with an even index.
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2
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1, 4, 50, 200, 1519, 6076, 36564, 146256, 770481, 3081924, 14934774, 59739096, 273905827, 1095623308, 4836291512, 19345166048, 83144608885, 332578435540, 1402399388442, 5609597553768, 23330003686119, 93320014744476, 384220628807964, 1536882515231856
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OFFSET
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8,2
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LINKS
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FORMULA
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G.f.: -x^8/((x-1)*(3*x-1)*(2*x+1)*(2*x-1)*(3*x+1)*(4*x-1)*(x+1)* (12*x^2-1)*(6*x^2-1)*(2*x^2-1)).
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EXAMPLE
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a(8) = 1: 1|2|3|4|5|6|7|8.
a(9) = 4: 19|2|3|4|5|6|7|8, 1|2|39|4|5|6|7|8, 1|2|3|4|59|6|7|8, 1|2|3|4|5|6|79|8.
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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