ディリクレ級数 でしょう
dirikurekyū sūdeshō
1. Dirichlet series; Probably a Dirichlet series
Noun
1. Dirichlet series; Probably a Dirichlet series
1. it seems; I think
2. right?; don't you agree?
1. series
1. geometric (progression, etc.)
1. Fourier series
1. power series
1. infinite series
1. geometric series
1. alternating series
1. harmonic series