Vrijeme: 11:06

Prebrojavanje u srcu <3 | Counting in our hearts <3 #4

Promotrimo niz a_n brojeva koje možemo dobiti zbrajanjem potencija broja 5 (dakle taj niz počinje ovako: 1,5,6,25,26,31,\dots). Ako je a_1=1, koliko je a_{200}?

Consider the sequence (a_n) of numbers that can be obtained as sums of distinct powers of 5 (so the sequence begins 1,5,6,25,26,31,\dots). If a_1=1, what is a_{200}?