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A067621
Let t = coefficient of x^(2n+1) in expansion of sin(x)/(1-x^2); a(n)=denominator(t)-numerator(t).
0
0, 1, 19, 799, 57527, 6327971, 39486539, 207304329751, 4337444437867, 19284277970756683, 8099396747717806859, 819658950869042054131, 2458976852607126162392999, 1726201750530202565999885299
OFFSET
0,3
COMMENTS
Old description: consider the power series of sin(x)/(x+1)=N(0)/D(0)*(x-x^2)+...+N(k)/D(k)*(x^(2k+1)-x^(2k+2))+...; then a(n)=D(n)-N(n).
FORMULA
a(n) is the difference between denominator and numerator of sum(i=0, n, (-1)^i/(2i+1)!)
MATHEMATICA
Denominator[#]-Numerator[#]&/@Table[Sum[(-1)^i/(2i+1)!, {i, 0, n}], {n, 0, 15}] (* Harvey P. Dale, Apr 18 2012 *)
PROG
(PARI) a(n)=local(t); if(n<0, 0, t=polcoeff(sin(x+O(x^(2*n+2)))/(1-x^2), 2*n+1); denominator(t)-numerator(t)) /* Michael Somos, Feb 01 2004 */
CROSSREFS
Sequence in context: A201708 A280625 A183441 * A206308 A369827 A135562
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Feb 02 2002
STATUS
approved