OFFSET
0,3
PROG
(PARI) a(n)=if(n<1, 0, (n+1)!*(2*n+1)!/4*polcoeff(1/sin(x+O(x^(2*n+2)))^2, 2*n-2))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michael Somos, Feb 14 2003
STATUS
approved