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A066532
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If n is odd a(n) = 1, if n is even a(n) = 2^(n-1).
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1
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1, 2, 1, 8, 1, 32, 1, 128, 1, 512, 1, 2048, 1, 8192, 1, 32768, 1, 131072, 1, 524288, 1, 2097152, 1, 8388608, 1, 33554432, 1, 134217728, 1, 536870912, 1, 2147483648, 1, 8589934592, 1, 34359738368, 1, 137438953472, 1, 549755813888, 1, 2199023255552
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OFFSET
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1,2
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COMMENTS
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Size of Frattini subgroup of the group of n X n signed permutations matrices (described in sequence A066051).
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LINKS
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FORMULA
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G.f.: 1/(1-x^2) + 2*x*(1+2*x^2)/(1-2*x^2). - Paul Barry, Jun 17 2006
a(n) = 2^n*(1-(-1)^n)/2+(1+(-1)^n)/2. - Paul Barry, Jun 17 2006
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MAPLE
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MATHEMATICA
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Table[ If[ OddQ[n], 1, 2^(n - 1)], {n, 42} ]
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PROG
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(PARI) { for (n=1, 350, if (n%2, a=1, a=2^(n-1)); write("b066532.txt", n, " ", a) ) } \\ Harry J. Smith, Feb 22 2010
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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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Sharon Sela (sharonsela(AT)hotmail.com), Jan 06 2002
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EXTENSIONS
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STATUS
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approved
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