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A290495
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The number of self-inverse Boolean functions of n variables.
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0
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1, 2, 10, 764, 46206736, 22481059424730751232, 135041388282796985771272553475002706667235246080, 5391278204075391354568253023229655921370142671388586075937736698667444395805138812903649656844450530044101525504
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = Sum_{k=0..2^(n-1)} (2^n)!/((2^n-2*k)! * k! * 2^k).
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MATHEMATICA
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Table[Sum[(2^n)!/((2^n - 2 k)!*k!*2^k), {k, 0, 2^(n - 1)}], {n, 0, 7}] (* Michael De Vlieger, Aug 04 2017 *)
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PROG
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(PARI) a(n) = sum(k=0, 2^(n-1), (2^n)!/((2^n-2*k)!*k!*2^k)) \\ Felix Fröhlich, Aug 04 2017
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CROSSREFS
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Cf. A000722 (invertible Boolean functions).
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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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