OFFSET
1,4
REFERENCES
W. Kohnen and D. Zagier, Values of L-series of modular forms at the center of the critical strip. Inv Math. 64 (1981) 175-198
FORMULA
See page 177 of reference. Also given by [theta_3(z)^4-(theta_2(z)^4)/8]*theta_3(z)*[(theta_2(z)*theta_4(z))^4]/16.
PROG
(PARI) {a(n) = local( A, t, T, U); if( n<0, 0, A = x * O(x^n); t = sum( k= 1, sqrtint( n), 2 * x^k^2, 1 + A); T = t^4; U = sum( k= 1, sqrtint( n), 2 * (-1)^k * x^k^2, 1 + A)^4; polcoeff( (7*T + U)/8 * (T - U)/16 * U * t, n))}
CROSSREFS
KEYWORD
sign
AUTHOR
Kok seng Chua (chuaks(AT)ihpc.nus.edu.sg), May 23 2000
STATUS
approved