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A236554
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Number of involutions in the quaternion ring over Z/(2^n)Z with i^2=j^2=1.
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1
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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invo11[n_] := Length@Reduce[a^2 - b^2 + c^2 + d^2 ==1 && 2 a b== 0 && 2 a c == 0 && 2 a d == 0, Modulus -> n]; Table[invo11[2^n], {n, 8}]
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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STATUS
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approved
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