Riddles and solution

[lyorn]

I posted some riddles at a blog, and have been asked for spoiler-less answers. So here's the riddles, the way I posted them. The answers are in the comments.


Not arithmetic at all:

20 1 18 4
M N B V ...
10 6 13 1 ...
1783 1848 1871 1947 ... (Only one number follows).

Double number sequence:

4 19 7 15 11 10 ...

Arithmetics on a hillside:

1 1 3 4 ...
0 2 2 2 ...
1 2 1 4 ...