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A138862 First two (i.e., the two most significant) digits of n-th Mersenne prime A000668(n). 4

%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 n-th 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

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Last modified December 4 21:14 EST 2020. Contains 338938 sequences. (Running on oeis4.)