Are you lucky enough to find these lucky numbers?
Discrete Mathematics
Level
4
A natural number \(a\) is called a lucky number if the sum of its digits is 7. Arrange all lucky numbers in an ascending order, and we get a sequence \(a_1 , a_2 , a_3 , \ldots \). If \(a_n = 2005\), compute \(a_{5n} \).
by
Raushan Sharma