Damien Algebra

Triangles	sticks
1	3
2	5
3	7
4	9
5	11
6	13
7	15
8	17
9	19
10	21
11	23
12	25
13	27
14	29
15	31

This is a pattern with matchsticks we worked out that to find out how many you need per a triangle, the  rule for the patten is (N x 2)+1.so for 20 fish (N=20).(20x2)+1=41