Question 258570
I think I understand your question
1 triangle = 3 sticks
2 triangles = 5 sticks
3 triangles = 7 sticks
 and so on . . . 
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2t + 1 = m
is the formula
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t=1 - -> 2(1) +1 = 3 = m
t=2 - - > 2(2) + 1 = 5 = m
t=3 - - > 2(3) + 1 = 7 = m
t=4 - - > 2(4) + 1 = 9 = m
t=5 - - > 2(5) + 1 = 11 = m
t=6 - - > 2(6) + 1 = 13 = m
t=10 - -> 2(10) + 1 = 21 = m
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Hope this helps