r - Extract every nth element of a vector

Question

I would like to create a vector in which each element is the i+6th element of another vector.

For example, in a vector of length 120 I want to create another vector of length 20 in which each element is value i, i+6, i+12, i+18... of the initial vector, i.e. I want to extract every 6th element of the original.

Answer 1

a <- 1:120
b <- a[seq(1, length(a), 6)]