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 1-7 of 7 results.

A247953 Numbers k such that 2^k + 33 is prime.

Original entry on oeis.org

2, 3, 6, 11, 12, 14, 15, 20, 30, 60, 68, 75, 108, 116, 135, 206, 210, 410, 446, 558, 851, 1482, 1499, 2039, 2051, 4196, 7046, 7155, 8735, 10619, 18420, 20039, 46719, 75348, 179790, 203018, 434246
Offset: 1

Views

Author

Vincenzo Librandi, Sep 28 2014

Keywords

Comments

Some terms correspond to probable primes. Lifchitz link shows the terms 179790 found by Donovan Johnson and 203018 by Lelio R Paula. - Jens Kruse Andersen, Sep 30 2014
a(38) > 5*10^5. - Robert Price, Nov 07 2015

Links

Crossrefs

Cf. A094076, A176926, A247957.
Cf. Numbers k such that 2^k + d is prime: (0,1,2,4,8,16) for d=1; A057732 (d=3), A059242 (d=5), A057195 (d=7), A057196 (d=9), A102633 (d=11), A102634 (d=13), A057197 (d=15), A057200 (d=17), A057221 (d=19), A057201 (d=21), A057203 (d=23), A157006 (d=25), A157007 (d=27), A156982 (d=29), A247952 (d=31), this sequence (d=33), A220077 (d=35).

Programs

  • Magma
    /* The code gives only the terms up to 851: */ [n: n in [1..1400]| IsPrime( 2^n + 33 )];
  • Maple
    A247957:=n->`if`(isprime(2^n+33),n,NULL): seq(A247957(n), n=0..1000); # Wesley Ivan Hurt, Sep 28 2014
  • Mathematica
    Select[Range[10000], PrimeQ[2^# + 33] &]
  • PARI
    is(n)=ispseudoprime(2^n+33) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

a(30)-a(34) from Jens Kruse Andersen, Sep 30 2014
a(35)-a(36) (discovered by Donovan Johnson and Lelio R Paula, respectively; see the Lifchitz link) added by Robert Price, Oct 04 2015
a(37) from Robert Price, Nov 07 2015

A247958 Numbers n such that 35^n + 2 is prime.

Original entry on oeis.org

0, 1, 15, 83, 1457, 3959, 5351, 5355, 41359, 50327, 54435
Offset: 1

Views

Author

Vincenzo Librandi, Sep 28 2014

Keywords

Comments

After 0, all terms are odd. - Bruno Berselli, Oct 01 2014
a(12) > 2*10^5. - Robert Price, Mar 21 2015

Links

Crossrefs

Cf. similar sequences listed in A247957.

Programs

  • Magma
    [n: n in [0..1000]| IsPrime(35^n+2)];
  • Maple
    A247958:=n->`if`(isprime(35^n+2),n,NULL): seq(A247958(n), n=0..1000); # Wesley Ivan Hurt, Sep 30 2014
  • Mathematica
    Select[Range[0, 10000], PrimeQ[35^# + 2] &]
  • PARI
    is(n)=ispseudoprime(35^n+2) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(9)-a(11) from Robert Price, Mar 21 2015

A247961 Numbers n such that 45^n + 2 is prime.

Original entry on oeis.org

0, 1, 2, 3, 4, 38, 40, 104, 114, 135, 417, 1251, 14786, 16720, 43831, 152659
Offset: 1

Views

Author

Vincenzo Librandi, Oct 02 2014

Keywords

Comments

Terms of A016969 and A113770 (except 1) are not in the sequence. - Bruno Berselli, Oct 02 2014
a(17) > 2*10^5. - Robert Price, Sep 15 2015

Links

Crossrefs

Cf. similar sequences listed in A247957.

Programs

  • Magma
    [n: n in [0..400]| IsPrime( 45^n + 2 )];
  • Maple
    A247961:=n->`if`(isprime(45^n+2),n,NULL): seq(A247961(n),n=1..500); # Wesley Ivan Hurt, Oct 02 2014
  • Mathematica
    Select[Range[0, 2000], PrimeQ[45^# + 2] &]
  • PARI
    is(n)=ispseudoprime(45^n+2) \\ Charles R Greathouse IV, Jun 06 2017

Extensions

a(13)-a(16) from Robert Price, Sep 15 2015

A247962 Numbers n such that 51^n + 2 is prime.

Original entry on oeis.org

0, 1, 5, 6, 15, 24, 25, 66, 72, 309, 330, 594, 1000, 1142, 1882, 2482, 2725, 30106, 65176, 85334
Offset: 1

Views

Author

Vincenzo Librandi, Oct 02 2014

Keywords

Comments

Numbers ending with 8 are not in the sequence. - Bruno Berselli, Oct 02 2014
a(21) > 2*10^5. - Robert Price, Jul 07 2015

Links

Crossrefs

Cf. similar sequences listed in A247957.

Programs

  • Magma
    [n: n in [0..300]| IsPrime( 51^n + 2 )];
  • Maple
    A247962:=n->`if`(isprime(51^n+2),n,NULL): seq(A247962(n),n=0..500); # Wesley Ivan Hurt, Oct 02 2014
  • Mathematica
    Select[Range[0, 2000], PrimeQ[51^# + 2] &]
  • PARI
    is(n)=ispseudoprime(51^n+2) \\ Charles R Greathouse IV, Jun 06 2017

Extensions

a(16)-a(20) from Robert Price, Jul 07 2015

A247959 Numbers n such that 39^n + 2 is prime.

Original entry on oeis.org

0, 1, 2, 5, 6, 13, 22, 93, 99, 132, 217, 539, 1185, 28840, 70666, 105456, 116749
Offset: 1

Views

Author

Vincenzo Librandi, Sep 28 2014

Keywords

Comments

Numbers ending with 4 are not in the sequence, since 39^n+2 is divisible by 11 for such numbers. - Bruno Berselli and M. F. Hasler, Oct 02 2014
a(18) > 2*10^5. - Robert Price, Apr 14 2015

Links

Crossrefs

Cf. similar sequences listed in A247957.

Programs

  • Magma
    [n: n in [0..500]| IsPrime(39^n+2)];
  • Mathematica
    Select[Range[0, 2000], PrimeQ[39^# + 2] &]
  • PARI
    for(n=0,9e9,ispseudoprime(39^n+2)&&print1(n",")) \\ M. F. Hasler, Oct 02 2014

Extensions

a(14)-a(17) from Robert Price, Apr 14 2015

A247960 Numbers n such that 41^n + 2 is prime.

Original entry on oeis.org

0, 1, 9, 23, 681, 2487
Offset: 1

Views

Author

Vincenzo Librandi, Sep 29 2014

Keywords

Comments

All terms > 0 are odd. - Robert Israel, Sep 29 2014
a(7) > 2*10^5. - Robert Price, May 08 2015

Crossrefs

Cf. similar sequences listed in A247957.

Programs

  • Magma
    [n: n in [0..600]| IsPrime( 41^n + 2 )];
  • Mathematica
    Select[Range[0, 2000], PrimeQ[41^# + 2] &]
  • PARI
    is(n)=ispseudoprime(41^n+2) \\ Charles R Greathouse IV, Jun 13 2017

A247963 Numbers n such that 57^n + 2 is prime.

Original entry on oeis.org

0, 1, 2, 4, 5, 54, 81, 310, 360, 1117, 1410, 3320, 66162
Offset: 1

Views

Author

Vincenzo Librandi, Oct 03 2014

Keywords

Comments

Numbers of the form 4*h+3 are not in the sequence, since in this case 57^n+2 is divisible by 5.
Numbers ending with 6 are not in the sequence, since in this case 57^n+2 is divisible by 11.
If n == 10 mod 16, 57^n+2 is divisible by 17. - Derek Orr, Oct 04 2014
a(14) > 2*10^5. - Robert Price, Jun 11 2015

Links

Crossrefs

Cf. similar sequences listed in A247957.

Programs

  • Magma
    [n: n in [0..300]| IsPrime( 57^n + 2 )];
  • Mathematica
    Select[Range[0, 2000], PrimeQ[57^# + 2] &]
  • PARI
    for(n=1,10^3,if(ispseudoprime(57^n+2),print1(n,", "))) \\ Derek Orr, Oct 04 2014

Extensions

Edited by Bruno Berselli, Oct 04 2014
a(13) from Robert Price, Jun 11 2015
Showing 1-7 of 7 results.

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