Stage 1	Stage 2	Stage 3
Cumulative sample size (control):	41	82	123
Cumulative sample size (treatment):	41	82	123
Maximum total sample size: 246
Upper bound	2.13	1.89	1.85
Lower bound	0.00	1.13	1.85
p-value for H1 ((stopping for) success)	0.018	0.031	0.033
p-value for H0 (stopping for a lack of efficacy)	0.500	0.130
Continue as planned at stage 1: 0.500 > p >  0.018
Continue as planned at stage 2: 0.130 > p >  0.031

The calculation was done with the R package MAMS