A138876 First 3 digits of n-th even perfect number.

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

Offset: 1

Author

Omar E. Pol, Apr 02 2008

Keywords

• base
• more
• nonn

Comments

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]

Links

• Jan Munch Pedersen, Known Perfect Numbers [From Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009] [Replaced with Wayback Machine link by _Felix Fröhlich_, Aug 04 2018]
• Omar E. Pol, Los numeros perfectos

Crossrefs

Cf. A000396, A135617, A138864, A138873, A138877.

First three digits of each term from A138877. [Steven Bi (chenhsi(AT)stanford.edu), Jan 18 2009]

Programs

Mathematica

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 *)

Extensions

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