Another proof of Euler’s formula for (2)

@inproceedings{Amo2011AnotherPO,
  title={Another proof of Euler’s formula for (2)},
  author={Enrique de Amo and Manuel D{\'i}az Carrillo and Juan Fern{\'a}ndez-S{\'a}nchez},
  year={2011}
}
We give a new proof of Euler's formula related to the sum of the inverses of even powers of positive integers.