s0 <- 0.125
s1 <- 0.125
za <- qnorm(0.95)
zb <- qnorm(0.8)
mu1 <- 0.55
mu0 <- 0.5
rho <- 0.6
n=(s0^2+s1^2-2*rho*s1*s0)*((za+zb)/(mu1-mu0))^2;n
## [1] 30.91279

If rho keep changing and other variables fixed.

If mu1 keep changing and other variables fixed.

If mu0 keep changing and other variables fixed.

If sigma keep changing and other variables fixed. 

s0 <- 0.125
s1 <- 0.125
za <- qnorm(0.95)
zb <- qnorm(0.8)
mu1 <- 0.55
mu0 <- 0.5
rho <- 0.6
n=(s0^2+s1^2-2*rho*s1*s0)*((za+zb)/(mu1-mu0))^2;n

#If rho keep changing and other variables fixed.
s0 <- 0.125
s1 <- 0.125
za <- qnorm(0.95)
zb <- qnorm(0.8)
mu1 <- 0.55
mu0 <- 0.5

rho <- seq(-1,1,length=50)
size=c()
for (i in 1:length(rho)){
n[i]=(s0^2+s1^2-2*rho[i]*s1*s0)*((za+zb)/(mu1-mu0))^2
size = c(size,n[i])}
plot(rho,size)

#If mu1 keep changing and other variables fixed.
s0 <- 0.125
s1 <- 0.125
za <- qnorm(0.95)
zb <- qnorm(0.8)
mu0 <- 0.5
rho <- 0.6

mu1 <- seq(mu0+0.02,1,length=50)
size=c()
for (i in 1:length(mu1)){
n[i]=(s0^2+s1^2-2*rho*s1*s0)*((za+zb)/(mu1[i]-mu0))^2
size = c(size,n[i])}
plot(mu1,size)

#If mu0 keep changing and other variables fixed.
s0 <- 0.125
s1 <- 0.125
za <- qnorm(0.95)
zb <- qnorm(0.8)
mu1 <- 0.80
rho <- 0.6

mu0 <- seq(0,mu1-0.02,length=50)
size=c()
for (i in 1:length(mu0)){
n[i]=(s0^2+s1^2-2*rho*s1*s0)*((za+zb)/(mu1-mu0[i]))^2
size = c(size,n[i])}
plot(mu0,size)

#If sigma keep changing and other variables fixed.
za <- qnorm(0.95)
zb <- qnorm(0.8)
mu0 <- 0.5
mu1 <- 0.55
rho <- 0.6

sigma = s0 = s1 = seq(0.05,0.5,length=50)
size=c()
for (i in 1:length(sigma)){
n[i]=(2*sigma[i]^2-2*rho*sigma[i]^2)*((za+zb)/(mu1-mu0))^2
size = c(size,n[i])}
plot(sigma,size)