The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A075615 Let P(k,X) = Product_{i=1..2*k} (X-1/cos(Pi*(2*i-1)/(4*k)) ) which is a polynomial with integer coefficients. Sequence gives array of coefficients for P(k,X). 0
 1, 0, -2, 1, 0, -8, 0, 8, 1, 0, -18, 0, 48, 0, -32, 1, 0, -32, 0, 160, 0, -256, 0, 128, 1, 0, -50, 0, 400, 0, -1120, 0, 1280, 0, -512, 1, 0, -72, 0, 840, 0, -3584, 0, 6912, 0, -6144, 0, 2048, 1, 0, -98, 0, 1568, 0, -9408, 0, 26880, 0, -39424, 0, 28672, 0, -8192, 1, 0, -128, 0, 2688, 0, -21504, 0, 84480, 0, -180224, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Included in A053120. LINKS EXAMPLE Array begins: 1, 0, -2; 1, 0, -8, 0, 8; 1, 0, -18, 0, 48, 0, -32; 1, 0, -32, 0, 160, 0, -256, 0, 128; 1, 0, -50, 0, 400, 0, -1120, 0, 1280, 0, -512; ... MATHEMATICA rows = 8; P[k_] := Product[x-1/Cos[Pi*((2*i-1)/(4*k))], {i, 1, 2*k}]; Table[CoefficientList[P[k], x] // Round // Reverse, {k, 1, rows}] // Flatten (* Jean-François Alcover, Nov 22 2016 *) CROSSREFS Sequence in context: A021896 A188835 A217735 * A195284 A351263 A076341 Adjacent sequences: A075612 A075613 A075614 * A075616 A075617 A075618 KEYWORD easy,sign,tabf AUTHOR Benoit Cloitre, Oct 11 2002 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 28 20:13 EST 2023. Contains 359905 sequences. (Running on oeis4.)