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A303588
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Number of partitions of n that contain exactly two isolated singletons.
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2
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1, 0, 2, 2, 7, 12, 32, 67, 169, 390, 985, 2412, 6209, 15871, 41867, 110797, 299836, 817612, 2268640, 6354409, 18058764, 51838340, 150704087, 442550971, 1314527780, 3943140077, 11953192954, 36580095663, 113048257691, 352564213025, 1109727658303
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OFFSET
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2,3
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LINKS
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MAPLE
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f:=proc(n, r) local j;
add(combinat:-bell(j-1)*binomial(n-j-1, j-r-1), j=1..floor((n+r)/2));
end;
[seq(f(n, 2), n=2..40)];
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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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