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 A066532 If n is odd a(n) = 1, if n is even a(n) = 2^(n-1). 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Size of Frattini subgroup of the group of n X n signed permutations matrices (described in sequence A066051). LINKS Harry J. Smith, Table of n, a(n) for n = 1..350 Index entries for linear recurrences with constant coefficients, signature (0,5,0,-4). FORMULA 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 E.g.f.: sinh(x) + sinh(x)^2. - Arkadiusz Wesolowski, Aug 13 2012 a(n) = (2 - (n mod 2))^(n - 1). - Wesley Ivan Hurt, Jul 21 2014 MAPLE A066532:=n->(2 - (n mod 2))^(n - 1): seq(A066532(n), n=1..50); # Wesley Ivan Hurt, Jul 21 2014 MATHEMATICA Table[ If[ OddQ[n], 1, 2^(n - 1)], {n, 42} ] PROG (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 CROSSREFS Cf. A066051, A081294. Sequence in context: A351708 A008309 A131175 * A205397 A020778 A118961 Adjacent sequences: A066529 A066530 A066531 * A066533 A066534 A066535 KEYWORD nonn,easy AUTHOR Sharon Sela (sharonsela(AT)hotmail.com), Jan 06 2002 EXTENSIONS More terms from Robert G. Wilson v, Jan 07 2002 More terms from Ralf Stephan, Jul 25 2003 STATUS approved

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Last modified December 3 19:10 EST 2023. Contains 367540 sequences. (Running on oeis4.)