Raabe's convergence test

Raabe's convergence test

[′räb·əz kən′vər·jəns ‚test]
(mathematics)
An infinite series with positive terms an where, for each n, an +1/ an = 1/(1 + bn ) will converge if, after a certain term, nbn always exceeds a fixed number greater than 1 and will diverge if nbn always is less than a fixed number less than or equal to 1.