cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A161323 Perfect numbers written in base 8.

Original entry on oeis.org

6, 34, 760, 17700, 177770000, 77777600000, 1777777000000, 177777777770000000000, 17777777777777777777700000000000000000000, 77777777777777777777777777777600000000000000000000000000000
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 07 2009

Keywords

Comments

All members end in 0, 1, 4, 5, or 6. Conjecturally, apart from the first two terms, all terms end in 0.

Links

Crossrefs

Cf. A000396, A135650, A160962.

Programs

  • Mathematica
    FromDigits[IntegerDigits[#,8]]&/@PerfectNumber[Range[10]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 08 2019 *)

Extensions

Edited by Charles R Greathouse IV, Mar 19 2010

A161322 a(n) = A000043(n) written in base 4.

Original entry on oeis.org

2, 3, 11, 13, 31, 101, 103, 133, 331, 1121, 1223, 1333, 20021, 21133, 103333, 202123, 203221, 302101, 1002131, 1011013, 2113121, 2123111, 2233031, 10313201, 11103011, 11222221, 22313101, 111003203, 122332213, 200033101, 310300123, 2320301213, 3101310221, 10303010323
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 07 2009

Keywords

Links

Crossrefs

Cf. A000043, A007090, A160962.

Programs

  • Mathematica
    Map[FromDigits[IntegerDigits[#, 4]] &, MersennePrimeExponent[Range[48]]] (* Amiram Eldar, Oct 16 2024 *)

Formula

a(n) = A007090(A000043(n)). - Amiram Eldar, Oct 16 2024

Extensions

Corrected (1301 replaced by 1223, 2021 replaced by 20021, 22311313 by 22313101) by R. J. Mathar, May 21 2010
a(32)-a(34) from Amiram Eldar, Oct 16 2024

A161496 Number of zeros in n-th even perfect number written in base 16.

Original entry on oeis.org

0, 0, 1, 1, 3, 4, 4, 7, 15, 22, 26, 31, 130, 151, 319, 550, 570, 804, 1063, 1105, 2422, 2485, 2803, 4984, 5425, 5802, 11124, 21560, 27625, 33012, 54022, 189209, 214858, 314446, 349567, 744055, 755344, 1743148, 3366729, 5249002, 6009145, 6491237, 7600614, 8145664, 9289166
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jun 11 2009

Keywords

Links

Crossrefs

Cf. A000396, A135650, A160962, A161323.

Formula

a(n) = floor((A000043(n)-1)/4). - Gerson Washiski Barbosa, May 29 2011

Extensions

Definition changed (inserting the word "even"), a(31) corrected and a(41)-a(45) added by Ivan Panchenko, Aug 04 2018
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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