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 1-4 of 4 results.

A139068 Primes of the form k!/9 + 1.

Original entry on oeis.org

4481, 611402462201343216650033936533361654773516861440000000001, 234195255375503079690400057633265510581087082006817356924774723468294901747510352675631491470712754833859385753600000000000000000001
Offset: 1

Views

Author

Artur Jasinski, Apr 07 2008

Keywords

Comments

For numbers k for which (9+k!)/9 is prime see A137390.

Crossrefs

Programs

  • Mathematica
    a = {}; Do[If[PrimeQ[(n! + 9)/9], AppendTo[a, (n! + 9)/9]], {n, 1, 150}]; a
    Select[Range[100]!/9+1,PrimeQ] (* Harvey P. Dale, Aug 17 2017 *)
  • PARI
    for(n=6,1e4,if(ispseudoprime(t=n!/9+1),print1(t", "))) \\ Charles R Greathouse IV, Jul 15 2011

Formula

a(n) = A139156(A137390(n)). - Amiram Eldar, Oct 14 2024

A139157 a(n) = (n!+10)/10.

Original entry on oeis.org

13, 73, 505, 4033, 36289, 362881, 3991681, 47900161, 622702081, 8717829121, 130767436801, 2092278988801, 35568742809601, 640237370572801, 12164510040883201, 243290200817664001, 5109094217170944001
Offset: 5

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Crossrefs

Programs

  • Mathematica
    Table[(n! + 10)/10, {n, 5, 30}]
  • PARI
    for(n=5, 20, a=(n!+10)/10; print1(a, ", ")) \\ Felix Fröhlich, Jul 07 2014

Extensions

Name corrected by Amiram Eldar, Oct 14 2024

A139151 a(n) = (n!+4)/4.

Original entry on oeis.org

7, 31, 181, 1261, 10081, 90721, 907201, 9979201, 119750401, 1556755201, 21794572801, 326918592001, 5230697472001, 88921857024001, 1600593426432001, 30411275102208001, 608225502044160001, 12772735542927360001
Offset: 4

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

Maximal solution for x such that x^2-y^2 = n! (because ((n! + 4)/4)^2 - ((n! - 4)/4)^2 = n! ). - Artur Jasinski, Mar 31 2012

Crossrefs

Programs

A139149 a(n) = (n!+2)/2.

Original entry on oeis.org

2, 4, 13, 61, 361, 2521, 20161, 181441, 1814401, 19958401, 239500801, 3113510401, 43589145601, 653837184001, 10461394944001, 177843714048001, 3201186852864001, 60822550204416001, 1216451004088320001, 25545471085854720001, 562000363888803840001
Offset: 2

Views

Author

Artur Jasinski, Apr 11 2008

Keywords

Comments

Also the number of (not necessarily maximal) cliques in the (n-1)-(weak) Bruhat graph. - Eric W. Weisstein, Jul 29 2018

Examples

			(1!+2)/2 = 3/2 is not an integer.
a(2) = (2!+2)/2 = 2.
		

Crossrefs

a(n) = (n!+m)/m: A038507 (m=1), this sequence (m=2), A139150 (m=3), A139151 (m=4), A139152 (m=5), A139153 (m=6), A139154 (m=7), A139155 (m=8), A139156 (m=9), A139157 (m=10).
Offsets for above sequences are Kempner numbers A002034.
For smallest number of the form (m!+n)/n see A139148.

Programs

Showing 1-4 of 4 results.