A nice upgrade, congrats on R(10^8). Also a small reminder that, just as lambda bodies, the bodies of 'cond' clauses have an implicit 'begin'.
Thanks! Going from R(20) to R(10^4) to R(10^8) just shows to me how insane the numbers you guys are pulling. Also I've removed the begins now from my function (and also changed the letrec to let).