I would like to announce a new unofficial record computation of the MRB constant that was finished on Sun 21 Sep 2014 18:35:06.

I really would like to see someone beat it with Maple!

It took 1 month 27 days 2 hours 45 minutes 15 seconds. I computed 3,014,991 digits of the MRB constant, (confirming my previous 2,00,000 or more digit computation was actually accurate to 2,009,993 digits), with Mathematica 10.0. I Used my version of Richard Crandall's code:

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(*Fastest (at MRB's end) as of 25 Jul 2014.*)

DateString[]

prec = 3000000;(*Number of required decimals.*)ClearSystemCache[];

T0 = SessionTime[];

expM[pre_] :=

Module[{a, d, s, k, bb, c, n, end, iprec, xvals, x, pc, cores = 12,

tsize = 2^7, chunksize, start = 1, ll, ctab,

pr = Floor[1.005 pre]}, chunksize = cores*tsize;

n = Floor[1.32 pr];

end = Ceiling[n/chunksize];

Print["Iterations required: ", n];

Print["end ", end];

Print[end*chunksize]; d = ChebyshevT[n, 3];

{b, c, s} = {SetPrecision[-1, 1.1*n], -d, 0};

iprec = Ceiling[pr/27];

Do[xvals = Flatten[ParallelTable[Table[ll = start + j*tsize + l;

x = N[E^(Log[ll]/(ll)), iprec];

pc = iprec;

While[pc < pr, pc = Min[3 pc, pr];

x = SetPrecision[x, pc];

y = x^ll - ll;

x = x (1 - 2 y/((ll + 1) y + 2 ll ll));];(*N[Exp[Log[ll]/ll],

pr]*)x, {l, 0, tsize - 1}], {j, 0, cores - 1},

Method -> "EvaluationsPerKernel" -> 4]];

ctab = ParallelTable[Table[c = b - c;

ll = start + l - 2;

b *= 2 (ll + n) (ll - n)/((ll + 1) (2 ll + 1));

c, {l, chunksize}], Method -> "EvaluationsPerKernel" -> 2];

s += ctab.(xvals - 1);

start += chunksize;

Print["done iter ", k*chunksize, " ", SessionTime[] - T0];, {k, 0,

end - 1}];

N[-s/d, pr]];

t2 = Timing[MRBtest2 = expM[prec];]; DateString[]

Print[MRBtest2]

MRBtest2 - MRBtest2M

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I used a six core Intel(R) Core(TM) i7-3930K CPU @ 3.20 GHz 3.20 GHz with 64 GB of RAM of which only 16 GB was used.

t2 From the computation was {1.961004112059*10^6, Null}.