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 A019320 Cyclotomic polynomials at x=2. 35
 2, 1, 3, 7, 5, 31, 3, 127, 17, 73, 11, 2047, 13, 8191, 43, 151, 257, 131071, 57, 524287, 205, 2359, 683, 8388607, 241, 1082401, 2731, 262657, 3277, 536870911, 331, 2147483647, 65537, 599479, 43691, 8727391, 4033, 137438953471, 174763, 9588151, 61681 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS T. D. Noe, Table of n, a(n) for n = 0..1000 Joerg Arndt, Matters Computational (The Fxtbook) FORMULA (lcm_{k=1..n} (2^k - 1))/lcm_{k=1..n-1} (2^k - 1), n > 1. - Vladeta Jovovic, Jan 20 2002 Let b(1) = 1 and b(n+1) = lcm(b(n), 2^n-1) then Phi(n,2) = b(n+1)/b(n) = a(n). - Thomas Ordowski, May 08 2013 a(0) = 2; for n > 0, a(n) = (2^n-1)/gcd(a(0)*a(1)*...*a(n-1), 2^n-1). - Thomas Ordowski, May 11 2013 MAPLE with(numtheory, cyclotomic); f := n->subs(x=2, cyclotomic(n, x)); seq(f(i), i=0..64); MATHEMATICA Join[{2}, Table[Cyclotomic[n, 2], {n, 1, 40}]] (* Jean-François Alcover, Jun 14 2013 *) PROG (PARI) vector(20, n, polcyclo(n, 2)) \\ Charles R Greathouse IV, May 18, 2011 CROSSREFS a(n) = A063696(n) - A063698(n) for up to n=104. Same sequence in binary: A063672. Cf. A054432, A020501, A034268. Sequence in context: A010757 A323943 A286616 * A201615 A033640 A112027 Adjacent sequences:  A019317 A019318 A019319 * A019321 A019322 A019323 KEYWORD nonn AUTHOR STATUS approved

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Last modified November 30 15:55 EST 2020. Contains 338807 sequences. (Running on oeis4.)