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.

Previous Showing 11-18 of 18 results.

A139198 a(n) = prime(n)!/10 - 1.

Original entry on oeis.org

11, 503, 3991679, 622702079, 35568742809599, 12164510040883199, 2585201673888497663999, 884176199373970195454361599999, 822283865417792281772556287999999
Offset: 3

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(Prime[n]! - 10)/10, {n, 3, 20}]
  • PARI
    a(n) = prime(n)!/10 - 1 \\ David A. Corneth, Jun 02 2017

Formula

a(n) = A039716(n)/10 - 1. - Elmo R. Oliveira, Jan 20 2023

A139173 a(n) = n!/3 - 1.

Original entry on oeis.org

1, 7, 39, 239, 1679, 13439, 120959, 1209599, 13305599, 159667199, 2075673599, 29059430399, 435891455999, 6974263295999, 118562476031999, 2134124568575999, 40548366802943999, 810967336058879999
Offset: 3

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

Original definition: Natural numbers of the form (n! - 3)/3.

Crossrefs

Cf. A139191: primes in this sequence. - M. F. Hasler, Apr 09 2009

Programs

  • Magma
    [Factorial(n)/3 -1: n in [3..25]]; // Vincenzo Librandi, Jul 20 2011
    
  • Mathematica
    Table[(n! - 3)/3, {n, 3, 20}]
  • PARI
    for(n=3,25, print1((n!-3)/3, ", ")) \\ G. C. Greubel, Oct 18 2018

Formula

E.g.f.: (6 - 3*x^2 - x^3)/(6*(1-x)) - exp(x). - G. C. Greubel, Oct 18 2018

Extensions

Edited by M. F. Hasler, Apr 09 2009

A139200 Numbers k such that (k!-5)/5 is prime.

Original entry on oeis.org

5, 11, 12, 16, 36, 41, 42, 47, 127, 136, 356, 829, 1863, 2065, 2702, 4509, 7498
Offset: 1

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

a(16) > 3000. - Ray G. Opao, Oct 05 2008
a(18) > 25000. - Robert Price, Nov 20 2016

Crossrefs

Programs

  • Magma
    [n: n in [5..500] | IsPrime((Factorial(n)-5) div 5)]; // Vincenzo Librandi, Nov 21 2016
  • Mathematica
    a = {}; Do[If[PrimeQ[(n! - 5)/5], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a (* Artur Jasinski *)

Extensions

a(13)-a(15) from Ray G. Opao, Oct 05 2008
a(16) from Serge Batalov, Feb 18 2015
a(17) from Robert Price, Nov 20 2016

A139201 Numbers k such that (k!-6)/6 is prime.

Original entry on oeis.org

4, 5, 7, 8, 11, 14, 16, 17, 18, 20, 43, 50, 55, 59, 171, 461, 859, 2830, 3818, 5421, 5593, 10118, 10880, 24350
Offset: 1

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

a(25) > 25000. - Robert Price, Dec 15 2016

Crossrefs

Programs

  • Maple
    a:=proc(n) if isprime((1/6)*factorial(n)-1)=true then n else end if end proc: seq(a(n),n=4..500); # Emeric Deutsch, Apr 29 2008
  • Mathematica
    a = {}; Do[If[PrimeQ[(n! - 6)/6], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a (* Artur Jasinski *)

Extensions

2 more terms from Emeric Deutsch, Apr 29 2008
More terms from Serge Batalov, Feb 18 2015
a(22)-a(24) from Robert Price, Dec 15 2016

A139202 Numbers k such that (k!-7)/7 is prime.

Original entry on oeis.org

7, 9, 20, 23, 46, 54, 57, 71, 85, 387, 396, 606, 1121, 2484, 6786, 9321, 11881, 18372
Offset: 1

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

a(19) > 25000. - Robert Price, Nov 05 2016

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[PrimeQ[(n! - 7)/7], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a (*Artur Jasinski*)

Extensions

More terms from Alexis Olson (AlexisOlson(AT)gmail.com), Nov 14 2008
a(13)-a(14) PRPs from Sean A. Irvine, Aug 05 2010
a(15)-a(18) PRP from Robert Price, Nov 05 2016

A139203 Numbers k such that (k!-8)/8 is prime.

Original entry on oeis.org

4, 6, 8, 10, 11, 16, 19, 47, 66, 183, 376, 507, 1081, 1204, 12111, 23181
Offset: 1

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

a(17) > 25000. - Robert Price, Oct 08 2016

Crossrefs

Programs

  • Maple
    a:=proc(n) if isprime((1/8)*factorial(n)-1)=true then n else end if end proc: seq(a(n),n=4..550); # Emeric Deutsch, May 07 2008
  • Mathematica
    a = {}; Do[If[PrimeQ[(n! - 8)/8], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a

Extensions

2 more terms from Emeric Deutsch, May 07 2008
More terms from Serge Batalov, Feb 18 2015
a(15)-a(16) from Robert Price, Oct 08 2016

A139204 Numbers k such that (k!-9)/9 is prime.

Original entry on oeis.org

6, 15, 17, 18, 21, 27, 29, 30, 37, 47, 50, 64, 125, 251, 602, 611, 1184, 1468, 5570, 10679, 15798, 21237
Offset: 1

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

a(20) > 10000. The PFGW program has been used to certify all the terms up to a(19), using a deterministic test which exploits the factorization of a(n) + 1. - Giovanni Resta, Mar 28 2014
a(23) > 25000. - Robert Price, Mar 29 2017

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[PrimeQ[(n! - 9)/9], Print[a]; AppendTo[a, n]], {n, 1, 300}]; a
  • PARI
    for(n=1,1000,if(floor(n!/9-1)==n!/9-1,if(ispseudoprime(n!/9-1),print(n)))) \\ Derek Orr, Mar 28 2014

Extensions

a(14)-a(16) from Derek Orr, Mar 28 2014
a(17)-a(19) from Giovanni Resta, Mar 28 2014
a(20)-a(22) from Robert Price, Mar 29 2017

A139207 Smallest father factorial prime p of order n = smallest prime of the form (p!-n)/n where p is prime.

Original entry on oeis.org

5, 2, 2947253997913233984847871999999, 29, 23, 19, 719, 4989599, 39520825343999, 11, 11058645491711999, 419, 479001599, 359, 7, 860234568201646565394748723848806399999999
Offset: 1

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

For smallest daughter factorial prime p of order n (smallest p such that (p!+n)/n = p!/n + 1 is prime) see A139074.
For smallest son factorial prime p of order n = smallest prime of the form (p!-n)/n where p is prime see A139206.
For more terms see A139206.

Crossrefs

Programs

  • Mathematica
    a = {}; Do[k = 1; While[ ! PrimeQ[(Prime[k]! - n)/n], k++ ]; Print[a]; AppendTo[a, (Prime[k]! - n)/n], {n, 1, 100}]; a
Previous Showing 11-18 of 18 results.