Task

The objective is to write a function that finds the sum of all positive multiples of 3 or 5 below n.

Show output for n = 1000.

This is is the same as Project Euler problem 1.

Extra credit: do this efficiently for n = 1e20 or higher.




m35 = function(n) sum(unique(c(
    seq(3, n-1, by = 3), seq(5, n-1, by = 5))))
m35(1000)   # 233168