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.

A139481 a(n) = A139480(n)/2.

Original entry on oeis.org

0, 1, 2, 5, 7, 8, 14, 29, 43, 52, 62, 259, 302, 638, 1100, 1139, 1607, 2125, 2210, 4843, 4969, 5605, 9967, 10849, 11603, 22247, 43120, 55250, 66023, 108044, 378418, 429715, 628892, 699133, 1488109, 1510687, 3486295, 6733457, 10498004, 12018290
Offset: 2

Views

Author

Artur Jasinski, Apr 22 2008

Keywords

Links

Crossrefs

Cf. A000043, A000668, A124477, A139479, A139480, A146768.

Programs

  • Mathematica
    (MersennePrimeExponent[Range[2, 48]] - 3)/2 (* Amiram Eldar, Oct 17 2024 *)

Formula

a(n) = A146768(n-1)-1. - R. J. Mathar, Mar 30 2011

Extensions

Edited by N. J. A. Sloane, May 23 2008

A124477 Numbers k such that 24k+7 is a Mersenne prime (A000668).

Original entry on oeis.org

0, 1, 5, 341, 5461, 21845, 89478485, 96076792050570581, 25790417485112089060398421, 6760803201217223474649083762005, 7089215977519551322153637654828504405
Offset: 1

Views

Author

Artur Jasinski, Dec 17 2006

Keywords

Comments

Note that 2^m - 1 can be expressed as 24*k+7 whenever m is an odd integer >= 3. - Robert Israel, Jul 08 2014

Links

Crossrefs

Cf. A000043, A000668, A139480.

Programs

  • Maple
    seq((numtheory:-mersenne([i+1])-7)/24, i=1..20); # Robert Israel, Jul 08 2014
  • PARI
    for(n=0, 1e20, k=0; if(ispseudoprime(24*n+7), while(2^k-1 < 24*n+7, k++); if(24*n+7==2^k-1, print1(n, ", ")))) \\ Felix Fröhlich, Jul 04 2014
  • PARI
    lista(nn) = {vmps = readvec("b000043.txt"); if (nn== 0, nn = #vmps); for (i=1, nn, mpi = 2^vmps[i]-8; if ((mpi % 24) == 0, print1(mpi/24, ", ")););} \\ Michel Marcus, Jul 05 2014

Formula

a(n) = (2^A000043(n+1)-8)/24. - Jeppe Stig Nielsen, Sep 17 2020

Extensions

a(11) corrected by Michel Marcus, Jul 05 2014

A121290 a(n) = (2^prime(n) - 8)/24 for n>=2.

Original entry on oeis.org

0, 1, 5, 85, 341, 5461, 21845, 349525, 22369621, 89478485, 5726623061, 91625968981, 366503875925, 5864062014805, 375299968947541, 24019198012642645, 96076792050570581, 6148914691236517205
Offset: 1

Views

Author

Lekraj Beedassy, Aug 24 2006

Keywords

Comments

Previous name was: (2^(p-3) - 1)/3, where p is an odd prime, i.e., p = A065091.

Crossrefs

Cf. A000043, A000668, A124477, A139479, A139480.

Programs

  • Mathematica
    Table[(2^Prime[n] - 8)/24, {n, 2, 100}] (* Artur Jasinski *)

Extensions

New name from Joerg Arndt, Jul 21 2017
Showing 1-3 of 3 results.

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

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