Question 67665
Use the following defintion to find the value of f(4).
f(1)=3 and 
f(n)= f(n-1) + n
You are given a starting point f(1)=3
You are given a rule for generating the next number in the sequence:
f(n) means any number of the sequence.
f(n-1) means the number just before the one you are generating
or the last one you generated.
n is the number of the sequence you are generating.

solution:
f(1)=3
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f(2)= f(1)+2 because f(1) comes just before f(2)
then you add 2 because that is the number of sequence element.
Since you were told f(1)=3, that is the 1st term below.
=3+2
=5 
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Now you go through the same process to generate f(3) 
f(3)=f(2)+3
=5+3
=8
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f(4)=f(3)+4
=8+4
=12
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Do you see that f(5)would be f(4)+5
=12+5
=17 
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Do you see that this process could go on forever?
That's what makes it recursive.
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Cheers,
Stan H.