It's called unrolled linked list. (https://en.m.wikipedia.org/wiki/Unrolled_linked_list https://en.m.wikipedia.org/wiki/Unrolled_linked_list). Note that if you

It's called unrolled linked list. (https://en.m.wikipedia.org/wiki/Unrolled_linked_list https://en.m.wikipedia.org/wiki/Unrolled_linked_list). Note that if you can make sure each chuck contains sqrt(N) elements, then you can achieve insertion/deletion/lookup in O(sqrt(N)) time