Subgroup growth in some pro-p groups

For a group G let a(n)(G) be the number of subgroups of index n and let b(n )(G) be the number of normal subgroups of index n. We show that a(p)k (SL21 ( Fp[[t]])) less than or equal to p(k(k+5)/2) for p >2. If Lambda = Fp[[t]] and p does not divide d or if Lambda = Z(p) and p not equal 2 or d not equ al 2, we show that for all k sufficiently large b(p)k(SLd1 (Lambda)) = b(p k+d 2 -1) (SLd1 (Lambda)). On the other hand if Lambda = Fp[[t]] and p divi des d, then b(n)(SLd1 (Lambda)) is not even bounded as a function of n.