|
|
A009563
|
|
E.g.f. sin(x/cosh(x)) (odd powers only).
|
|
4
|
|
|
1, -4, 56, -1688, 84160, -6141312, 613282944, -80158806016, 13267800137728, -2710082835353600, 669033814167273472, -196220826200422416384, 67398310755666413387776, -26784943833122921085534208
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 2*Sum_{m=0..n-1} binomial(2*n+1,2*m+1)*(Sum_{j=0..(n-m)} binomial(m+j-1/2,j)*4^(n-m-j)*Sum_{i=0..j} (i-j)^(2*n-2*m)* binomial(2*j,i)*(-1)^(m+j-i))) + (-1)^n. - Vladimir Kruchinin, Jun 16 2011
|
|
MATHEMATICA
|
With[{nn=30}, Take[CoefficientList[Series[Sin[x/Cosh[x]], {x, 0, nn}], x] Range[ 0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Dec 24 2017 *)
|
|
PROG
|
(Maxima) a(n):=2*sum(binomial(2*n+1, 2*m+1)*(sum(binomial(m+j-1/2, j)*4^(n-m-j)*sum((i-j)^(2*n-2*m)*binomial(2*j, i)*(-1)^(m+j-i), i, 0, j), j, 0, (n-m))), m, 0, n-1)+(-1)^n; /* Vladimir Kruchinin, Jun 16 2011 */
(PARI) my(x='x+O('x^50)); v=Vec(serlaplace(sin(x/cosh(x)))); vector((#v-1)\2 , n, v[2*n-1]) \\ G. C. Greubel, Jan 21 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|