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 1-5 of 5 results.

A139224 M(M-1)/2, where M is Mersenne prime A000668(n).

Original entry on oeis.org

3, 21, 465, 8001, 33542145, 8589737985, 137438167041, 2305843005992468481, 2658455991569831742348849606740148225, 191561942608236107294793377465333618488307184098607105
Offset: 1

Views

Author

Omar E. Pol, May 10 2008

Keywords

Comments

Perfect number A000396(n) minus Mersenne prime A000668(n).

Links

Crossrefs

Cf. A000217, A000396, A000668, A036689, A139096, A139115, A139116, A139223, A139225, A139226, A139256, A139306.

Formula

a(n) = A000668(n)*(A000668(n)-1)/2.
a(n) = A000396(n)-A000668(n).

Extensions

More terms from Max Alekseyev, Mar 09 2009

A139115 a(n) = p*(p - 1), where p is A000043(n).

Original entry on oeis.org

2, 6, 20, 42, 156, 272, 342, 930, 3660, 7832, 11342, 16002, 270920, 367842, 1634562, 4851006, 5200680, 10345872, 18083756, 19558506, 93867032, 98813540, 125720156, 397464032, 470911700, 538634472, 1979938512, 7437768806, 12210802506
Offset: 1

Views

Author

Omar E. Pol, May 10 2008

Keywords

Links

Crossrefs

Cf. A000043, A036689, A139306, A139307, A139116, A139223, A139224, A139225, A139226.

Programs

  • Mathematica
    #(#-1)&/@MersennePrimeExponent[Range[30]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 15 2020 *)

Formula

a(n) = A000043(n)*(A000043(n) - 1).

Extensions

More terms from Vincenzo Librandi, May 11 2010

A139223 M*(M-1), where M is Mersenne prime A000668(n).

Original entry on oeis.org

6, 42, 930, 16002, 67084290, 17179475970, 274876334082, 4611686011984936962, 5316911983139663484697699213480296450, 383123885216472214589586754930667236976614368197214210
Offset: 1

Views

Author

Omar E. Pol, May 10 2008

Keywords

Links

Crossrefs

Cf. A000668, A036689, A139115, A139116, A139224, A139225, A139226, A139256.

Formula

a(n) = A000668(n)*(A000668(n)-1).

Extensions

More terms from R. J. Mathar, Jun 24 2009

A139225 M(M-1)/3, where M is Mersenne prime A000668(n).

Original entry on oeis.org

2, 14, 310, 5334, 22361430, 5726491990, 91625444694, 1537228670661645654, 1772303994379887828232566404493432150, 127707961738824071529862251643555745658871456065738070, 8776024305713098891493168973639040433964428736682367693182293334, 9649340769776349618630915417390658987602357538676244438223111363610210030934
Offset: 1

Views

Author

Omar E. Pol, May 10 2008

Keywords

Comments

Terms from a(13) on have 314 or more digits and are not listed for that reason. - R. J. Mathar, May 11 2008

Crossrefs

Cf. A000668, A036689, A139115, A139116, A139223, A139224, A139226.

Formula

a(n)=A000668(n)*(A000668(n)-1)/3.

Extensions

More terms from R. J. Mathar, May 11 2008

A139226 M(M-1)/6, where M is Mersenne prime A000668(n).

Original entry on oeis.org

1, 7, 155, 2667, 11180715, 2863245995, 45812722347, 768614335330822827, 886151997189943914116283202246716075, 63853980869412035764931125821777872829435728032869035, 4388012152856549445746584486819520216982214368341183846591146667, 4824670384888174809315457708695329493801178769338122219111555681805105015467
Offset: 1

Views

Author

Omar E. Pol, May 10 2008

Keywords

Comments

Perfect number A000396(n) minus Mersenne prime A000668(n), divided by 3.
Terms from a(13) on have 313 or more digits and are not listed for that reason. - R. J. Mathar, May 11 2008

Links

Crossrefs

Cf. A000217, A000396, A000668, A036689, A139096, A139115, A139116, A139223, A139224, A139225, A139256, A139306.

Formula

a(n) = A000668(n)*(A000668(n)-1)/6 = A139223(n)/6 = A139224(n)/3.
a(n) = (A000396(n)-A000668(n))/3.

Extensions

More terms from R. J. Mathar, May 11 2008
Showing 1-5 of 5 results.

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