Problem 57 (difficulty: 6/10)

Express the sums below in closed form!


 (1)  \(\displaystyle u_0 +u_3 +\ldots + u_{3n} ;\)
 (2)  \(\displaystyle u_1 u_2 +\ldots + u_{2n-1} u_{2n} .\)

Give me another random problem!

Subject, section:
Requested difficulty:
Request for a concrete problem:I want problem no.

Supported by the Higher Education Restructuring Fund allocated to ELTE by the Hungarian Government