B[1-10] <- A[2-6, and 11-16]

# example 1 column matrix
A <- matrix(1:20, ncol = 1)

B <- A[ c(2:6, 11:16), 1 ]
dim(B)
# NULL
class(B)
# [1] "integer"

B <- A[ c(2:6, 11:16), 1, drop = FALSE ]
dim(B)
# [1] 11  1
class(B)
# [1] "matrix"

B = as.matrix (c(A[2:6,1],A[11:16,1]))