MathDB
Problems
Contests
Undergraduate contests
Putnam
1978 Putnam
B2
Putnam 1978 B2
Putnam 1978 B2
Source: Putnam 1978
May 2, 2022
Putnam
Summation
Double Sum
Problem Statement
Express
∑
n
=
1
∞
∑
m
=
1
∞
1
m
2
n
+
m
n
2
+
2
m
n
\sum_{n=1}^{\infty} \sum_{m=1}^{\infty} \frac{1}{m^2 n +m n^2 +2mn }
n
=
1
∑
∞
m
=
1
∑
∞
m
2
n
+
m
n
2
+
2
mn
1
as a rational number.
Back to Problems
View on AoPS