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.

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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

Cf. A139074, A139189, A139190, A139191, A139192, A139193, A139194, A139195, A139196, A139197, A139198, A136019, A136020, A136026, A136027.

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

A139073 Smallest prime number of the form (n+k!)/n.

Original entry on oeis.org

2, 2, 3, 7, 1009, 2, 5702401, 631, 4481, 13, 566092801, 3, 23452949585516450807808000001, 259201, 337, 2521, 3553839003727872684550301886383176323956736000000001, 41
Offset: 1

Views

Author

Artur Jasinski, Apr 07 2008

Keywords

Links

Crossrefs

Cf. A007749, A020458, A082672, A089085, A089130, A117141, A136019, A136020, A136026, A136027, A137390, A139056-A139066, A139068, A139070-A139075.

Programs

  • Mathematica
    a = {}; Do[ k = 1; While[ ! PrimeQ[ (k! + n)/n ], k++ ]; AppendTo[ a, (k! + n)/n ], {n, 1, 100} ]; a [Corrected May 06 2008]
  • PARI
    a(n)=my(k,t);until(denominator(t=k++!/n+1)==1&&ispseudoprime(t),);t \\ Charles R Greathouse IV, Jul 19 2011

Formula

a(n) = (n + A139072(n)!)/n. - Amiram Eldar, Oct 14 2024

A139091 a(n) = largest prime divisor of the number prime(n)!/9 + 1.

Original entry on oeis.org

17, 827, 22319071, 1718296754087, 35662591735219, 477262171871, 1609727002420791262479701, 146215297537890243023, 2020914387433686758547638152441, 1073774770807266077323
Offset: 4

Views

Author

Artur Jasinski, Apr 08 2008

Keywords

Links

Crossrefs

Cf. A082672, A089085, A089130, A117141, A007749, A139056-A139066, A020458, A139068, A137390, A139070-A139075, A136019, A136020, A136026, A136027, A139089-A139092.

Programs

  • Mathematica
    a = {}; Do[w = FactorInteger[(Prime[n]! + 9)/9]; AppendTo[a, Last[w][[1]]], {n, 4, 16}]; a

A139090 a(n) = smallest prime divisor of the number prime(n)!/9 + 1.

Original entry on oeis.org

3, 31, 31, 23, 379, 83, 610301, 293, 101, 47, 281, 127, 278174297, 2971, 109, 5090615254324820333, 46411, 106087, 269, 288931, 59047158151, 120871, 373, 19140822523, 56595118147, 1708207, 331, 38749, 157, 2927, 2143
Offset: 4

Views

Author

Artur Jasinski, Apr 08 2008

Keywords

Crossrefs

Cf. A082672, A089085, A089130, A117141, A007749, A139056-A139066, A020458, A139068, A137390, A139070-A139075, A136019, A136020, A136026, A136027, A139089-A139092.

Programs

  • Mathematica
    a = {}; Do[w = FactorInteger[(Prime[n]! + 9)/9]; AppendTo[a, First[w][[1]]], {n, 4, 16}]; a
Table[FactorInteger[p!/9+1][[1,1]],{p,Prime[Range[4,35]]}] (* Harvey P. Dale, Sep 19 2020 *)

Extensions

More terms from Jon E. Schoenfield, Jul 16 2010
Previous Showing 31-34 of 34 results.

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

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