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.

A180269 Primes of the form 3^n+3*n+1.

Original entry on oeis.org

2, 7, 37, 36472996377170786527, 2954312706550833698779, 3990838394187339929534246675572349035477, 2120895147045314119491609587512844743630072393, 228532044137599177017869183161846685251274404207185590172004697234871412029099114059347
Offset: 1

Views

Author

Graziano Aglietti (mg5055(AT)mclink.it), Aug 23 2010

Keywords

Comments

Terms a(9) through a(12) have, respectively, 93, 94, 149, and 156 digits. - Harvey P. Dale, May 11 2013

Crossrefs

Programs

  • Mathematica
    Select[Table[3^n+3n+1,{n,0,100}],PrimeQ] (* Harvey P. Dale, May 11 2013 *)
  • PARI
    for(i=0,200,x=3^i+3*i+1;if(isprime(x),print1(x", ")))

Extensions

a(8) from Harvey P. Dale, May 11 2013

A301632 Numbers k such that 3^k + k + 1 is a prime.

Original entry on oeis.org

0, 1, 3, 15, 45, 117, 159, 3739, 3777, 9703, 10623, 21459, 86595
Offset: 1

Views

Author

Seiichi Manyama, Mar 25 2018

Keywords

Comments

a(14) > 200000. - Michael S. Branicky, May 19 2025

Crossrefs

A182327 gives the primes.

Programs

  • Maple
    a:=n->`if`(isprime(3^k+k+1),k,NULL): seq(a(k),k=0..6000); # Muniru A Asiru, Mar 25 2018
  • Mathematica
    Flatten[{0, Select[Range[5000], PrimeQ[3^# + # + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *)
  • PARI
    for(n=0, 1000, if(isprime(3^n+n+1), print1(n", ")))

Extensions

a(8)-a(9) from Muniru A Asiru, Mar 25 2018
a(10)-a(11) from Vaclav Kotesovec, Mar 25 2018
a(12) from Altug Alkan, Apr 01 2018
a(13) from Giovanni Resta, Apr 06 2018

A301634 Numbers k such that 2^k + 2*k + 1 is prime.

Original entry on oeis.org

0, 1, 5, 13, 65, 85, 229, 2005, 3875, 3919, 5417, 8819, 11899, 16668, 19445, 28242, 33407, 37918, 40594, 141251
Offset: 1

Views

Author

Seiichi Manyama, Mar 25 2018

Keywords

Comments

Next term, if it exists, is greater than 50000. Terms up to 229 correspond to provable primes. The terms greater than or equal to 2005 correspond to probable primes. - Jon E. Schoenfield and Vaclav Kotesovec, Mar 27 2018

Crossrefs

A163115 gives the primes.
Numbers k such that b^k + b*k + 1 is prime: this sequence (b=2), A171058 (b=3), A301635 (b=5).
Cf. A176691.

Programs

  • Maple
    a:=k->`if`(isprime(2^k+2*k+1),k,NULL): seq(a(k),k=0..6000); # Muniru A Asiru, Mar 25 2018
  • Mathematica
    Flatten[{0, Select[Range[5000], PrimeQ[2^# + 2*# + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *)
  • PARI
    for(n=0, 500, if(isprime(2^n+2*n+1), print1(n", ")))

Extensions

a(9)-a(15) from Vaclav Kotesovec, Mar 25 2018
a(16), a(18)-a(19) from Jon E. Schoenfield, Mar 26 2018
a(17) inserted by and a(20) from Michael S. Branicky, Jun 23 2024

A301635 Numbers k such that 5^k + 5*k + 1 is prime.

Original entry on oeis.org

0, 1, 11, 25, 35, 85, 499, 1403, 3511, 3739, 8005
Offset: 1

Views

Author

Seiichi Manyama, Mar 25 2018

Keywords

Comments

a(12), if it exists, is greater than 20000. - Vaclav Kotesovec, Mar 25 2018
a(12), if it exists, is greater than 80000. - Michael S. Branicky, Sep 03 2024

Crossrefs

A301638 gives the primes.

Programs

  • Mathematica
    Flatten[{0, Select[Range[1000], PrimeQ[5^# + 5*# + 1] &]}] (* Vaclav Kotesovec, Mar 25 2018 *)
  • PARI
    for(n=0, 500, if(isprime(5^n+5*n+1), print1(n", ")))

Extensions

a(8)-a(11) from Vaclav Kotesovec, Mar 25 2018
Showing 1-4 of 4 results.