4.1.1 Mathematical Induction.sagews

s = 1
n = 5
for k in [2..n]:
    s = s + k
s
print '1 + 2 + ... + ', n , '=', s

15 1 + 2 + ... + 5 = 15

n*(n+1)/2
42

15 42

f=x
n=50
print '1 + 2 + ... +', n, '=', sum(f,x,1,n)

n*(n+1)/2

1275