R's standard deviation is off

test_sd.r

## Input data.
y = c(-0.25, 0.68, 0.94, 1.15, 1.20, 1.26, 1.26,
       1.34, 1.38, 1.43, 1.49, 1.49, 1.55, 1.56,
       1.58, 1.65, 1.69, 1.70, 1.76, 1.77, 1.81,
       1.91, 1.94, 1.96, 1.99, 2.06, 2.09, 2.10,
       2.14, 2.15, 2.23, 2.24, 2.26, 2.35, 2.37,
       2.40, 2.47, 2.54, 2.62, 2.64, 2.90, 2.92,
       2.92, 2.93, 3.21, 3.26, 3.30, 3.59, 3.68,
       4.30, 4.64, 5.34, 5.42, 6.01)

sd(y)
sqrt(sum((y - mean(y))**2)/length(y))

## [1] 1.18287
## [1] 1.171866