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 A019320 Cyclotomic polynomials at x=2. 33

%I

%S 2,1,3,7,5,31,3,127,17,73,11,2047,13,8191,43,151,257,131071,57,524287,

%T 205,2359,683,8388607,241,1082401,2731,262657,3277,536870911,331,

%U 2147483647,65537,599479,43691,8727391,4033,137438953471,174763,9588151,61681

%N Cyclotomic polynomials at x=2.

%H T. D. Noe, <a href="/A019320/b019320.txt">Table of n, a(n) for n = 0..1000</a>

%H Joerg Arndt, <a href="http://www.jjj.de/fxt/#fxtbook">Matters Computational (The Fxtbook)</a>

%H <a href="/index/Cy#CyclotomicPolynomialsValuesAtX">Index entries for cyclotomic polynomials, values at X</a>

%F (lcm_{k=1..n} (2^k - 1))/lcm_{k=1..n-1} (2^k - 1), n > 1. - _Vladeta Jovovic_, Jan 20 2002

%F 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

%F 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

%p with(numtheory,cyclotomic); f := n->subs(x=2,cyclotomic(n,x)); seq(f(i),i=0..64);

%t Join[{2}, Table[Cyclotomic[n, 2], {n, 1, 40}]] (* _Jean-François Alcover_, Jun 14 2013 *)

%o (PARI) vector(20,n,polcyclo(n,2)) \\ _Charles R Greathouse IV_, May 18, 2011

%Y A019320(n) = A063696(n) - A063698(n) for up to n=104.

%Y Same sequence in binary: A063672.

%Y Cf. A054432, A020501, A034268.

%K nonn

%O 0,1

%A _Simon Plouffe_

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Last modified November 16 04:54 EST 2018. Contains 317257 sequences. (Running on oeis4.)