Why the following code works

```
using Combinatorics
all_sequences = []
for i in 2:4
for j in permutations(1:4, i)
push!(all_sequences, collect(j))
end
end
```

and this one does not

```
using Combinatorics
all_sequences = Array{Array{Int64,1},1}[]
for i in 2:4
for j in permutations(1:4, i)
push!(all_sequences, collect(j))
end
end
```

and gives the error message: `ERROR: MethodError: Cannot `convert` an object of type Int64 to an object of type Array{Int64,1}`

.

When I specify the array `all_sequences`

type as `Array{Array{Int64,1},1}`

, I got the error. However, the array `all_sequences`

type is nothing but `Array{Array{Int64,1},1}`

, no?