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A373752
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a(n) = Sum_{k=0..n-2} A205497(n, k) * (1 - k mod 2) if n >= 2, a(0) = a(1) = 1.
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1
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1, 1, 1, 1, 2, 8, 33, 136, 670, 3968, 25593, 176896, 1344154, 11184128, 99897361, 951878656, 9687175862, 104932671488, 1202872541673, 14544442556416, 185158504589938, 2475749026562048, 34676498435503489, 507711943253426176, 7757079744889072462, 123460740095103991808
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OFFSET
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0,5
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COMMENTS
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Number of linear extensions in L(eps Z_n) that have an even number of descents. (See Petersen and Yan Zhuang, p. 6.)
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LINKS
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FORMULA
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MAPLE
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enum := L -> ListTools:-Enumerate(L):
seq(add(c[2]*irem(c[1], 2), c = enum([A205497row(n)])), n = 0..25);
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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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