# Van Eck sequence

This page is a solution to the task Van Eck sequence in the Rosetta Code, written in Fōrmulæ.

### Description (from Rosetta Code)

 The sequence is generated by following this pseudo-code: ```A: The first term is zero. Repeatedly apply: If the last term is *new* to the sequence so far then: B: The next term is zero. Otherwise: C: The next term is how far back this last term occured previousely. ``` Example Using A: `0` Using B: `0 0` Using C: `0 0 1` Using B: `0 0 1 0` Using C: (zero last occured two steps back - before the one) `0 0 1 0 2` Using B: `0 0 1 0 2 0` Using C: (two last occured two steps back - before the zero) `0 0 1 0 2 0 2 2` Using C: (two last occured one step back) `0 0 1 0 2 0 2 2 1` Using C: (one last appeared six steps back) `0 0 1 0 2 0 2 2 1 6` etc. Task Create a function/proceedure/method/subroutine/... to generate the Van Eck sequence of numbers. Use it to display here, on this page: The first ten terms of the sequence. Terms 991 - to - 1000 of the sequence. References

### Use cases

Let us store the complete sequence:

The first ten terms of the sequence:

Terms 991 - to - 1000 of the sequence: