%I
%S 3,7,31,12,81,13,52,21,23,61,16,17,68,53,10,14,44,25,19,28,47,34,28,
%T 43,44,40,85,53,52,51,74,17,12,41,81,62,12,43,92,12,29,12,31,12,20,16,
%U 31
%N First two (i.e., the two most significant) digits of nth Mersenne prime A000668(n).
%H L. C. Noll, <a href="http://www.isthe.com/chongo/tech/math/prime/mersenne.html">Mersenne Prime Digits and Names</a>.
%t Join[{3,7},FromDigits[Take[IntegerDigits[#],2]]&/@ (2^MersennePrimeExponent[ Range[ 3,47]]1)] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Aug 01 2020 *)
%Y Cf. A000668, A080173, A138863, A138864, A138865, A138866.
%K base,nonn
%O 1,1
%A _Omar E. Pol_, Apr 02 2008
%E a(40)a(47) from _Ivan Panchenko_, Aug 03 2018
%E Definition clarified by _Harvey P. Dale_, Aug 01 2020
