A099590 2^(n-1) times coefficient of x in (1+x)^n mod U(n,x), U the Chebyshev polynomials.

0, 4, 14, 32, 77, 192, 452, 1024, 2299, 5120, 11270, 24576, 53241, 114688, 245768, 524288, 1114103, 2359296, 4980746, 10485760, 22020085, 46137344, 96469004, 201326592, 419430387, 872415232, 1811939342, 3758096384, 7784628209

Offset: 1

Author

Ralf Stephan, Oct 24 2004

Keywords

• nonn

Crossrefs

Cf. A099586.

Formula

Apparently, a(n+1) = (n+1)2^n - (n+2)/4 * (I^n + (-I)^n).

Empirical g.f.: x^2*(x+2)*(x^2-2*x+2) / ((2*x-1)^2*(x^2+1)^2). - Colin Barker, Jul 16 2013