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A138876
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First 3 digits of n-th even perfect number.
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1
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6, 28, 496, 812, 335, 858, 137, 230, 265, 191, 131, 144, 235, 141, 541, 108, 994, 335, 182, 407, 114, 598, 395, 931, 100, 811, 365, 144, 136, 131, 278, 151, 838, 849, 331, 194, 811, 955, 427, 793, 448, 746, 497, 775, 204, 144, 500
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OFFSET
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1,1
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COMMENTS
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As of August 6, 2018, GIMPS reports that all Mersenne primes through the 47th have been positively identified, i.e., that there are no further such primes below the 47th. Thus, the sequence through a(47), i.e., through the term 500, is complete. Additional terms (169, 451, 109) are correct but it is still possible that more terms may be found above a(47) but below a(50). [Harvey P. Dale, Jul 17 2011] [Updated by Ivan Panchenko, Aug 06 2018]
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LINKS
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MATHEMATICA
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f[n_] := Block[{e, p, mpe = MersennePrimeExponent@ n}, p = (2^mpe - 1) 2^(mpe - 1); e = IntegerLength@ p - 3; If[e < 1, p, Quotient[p, 10^e]]]; Array[f, 44] (* Robert G. Wilson v, Aug 06 2018 *)
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CROSSREFS
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First three digits of each term from A138877. [Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009]
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KEYWORD
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base,more,nonn
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AUTHOR
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EXTENSIONS
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a(15)-a(31) added by Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009
Corrected a(27) and added a(32) through a(40) by Harvey P. Dale, Jul 17 2011
Definition changed (inserting the word "even") and a(41)-a(47) added by Ivan Panchenko, Aug 04 2018
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STATUS
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approved
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