login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A138876 First 3 digits of n-th even perfect number. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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

Table of n, a(n) for n=1..47.

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

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 *)

CROSSREFS

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

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

Sequence in context: A325021 A325025 A325023 * A326145 A174633 A325637

Adjacent sequences:  A138873 A138874 A138875 * A138877 A138878 A138879

KEYWORD

base,more,nonn

AUTHOR

Omar E. Pol, Apr 02 2008

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 4 06:41 EDT 2020. Contains 334822 sequences. (Running on oeis4.)