OFFSET
0,4
COMMENTS
Equals the row sums of triangle A326798.
FORMULA
EXAMPLE
E.g.f.: B(x) = 1 - x^2/2! + x^4/4! + 119*x^6/6! - 671*x^8/8! - 118801*x^10/10! + 1578721*x^12/12! + 472546983*x^14/14! - 11434861759*x^16/16! - 5281001286433*x^18/18! + 202651641610561*x^20/20! + ....
PROG
(PARI) {a(n) = my(Ax=x, Bx=1, Cx=x, Ay=y, By=y, Cy=1);
for(i=0, 2*n+1,
Ax = 0 + intformal( Bx*Cy - Cx*By, x) + O(x^(2*n+2));
Bx = 1 + intformal( Cx*Ay - Ax*Cy, x) + O(x^(2*n+2));
Cx = 0 + intformal( Ax*By - Bx*Ay, x) + O(x^(2*n+2));
Ay = 0 + intformal( By*Cx - Cy*Bx, y) + O(y^(2*n+2));
By = 0 + intformal( Cy*Ax - Ay*Cx, y) + O(y^(2*n+2));
Cy = 1 + intformal( Ay*Bx - By*Ax, y) + O(y^(2*n+2));
);
sum(k=0, n\2, (2*n)! * polcoeff( polcoeff(Bx, 2*n-2*k, x), 2*k, y))}
for(n=0, 20, print1( a(n), ", "))
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Aug 05 2019
STATUS
approved