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 1-10 of 12 results. Next

A116724 Erroneous version of A076680.

Original entry on oeis.org

0, 1, 2, 4, 7, 8, 9, 13, 16, 28, 54, 129, 190
Offset: 1

Views

Author

Keywords

References

  • From a posting to the Math Fun and Sequence Fans mailing lists, Sep 14 2010.

A051915 Numbers k such that 2*k! + 1 is prime.

Original entry on oeis.org

0, 1, 2, 3, 5, 12, 18, 35, 51, 53, 78, 209, 396, 4166, 9091, 9587, 13357, 15917, 17652, 46127, 66480
Offset: 1

Views

Author

Labos Elemer, Dec 18 1999

Keywords

Comments

Used PrimeForm to prove primality for n = 4166 (classical N-1 test). - David Radcliffe, May 28 2007
a(22) > 80000. - Serge Batalov, Jun 09 2025

Examples

			k = 5 is here because 2*5! + 1 = 241 is prime.

Crossrefs

Cf. A002981, A076679, A076680, A076681, A076682, A076683, A178488, A180626, A126896.

Programs

Extensions

4166 from David Radcliffe, May 28 2007
More terms from Serge Batalov, Feb 18 2015
a(21) from Serge Batalov, Jun 08 2025

A099350 Numbers k such that 4*k! - 1 is prime.

Original entry on oeis.org

0, 1, 2, 3, 5, 6, 10, 11, 51, 63, 197, 313, 579, 1264, 2276, 2669, 4316, 4382, 4678, 7907, 10843
Offset: 1

Views

Author

Brian Kell, Oct 12 2004

Keywords

Comments

a(19) > 4570. - Jinyuan Wang, Feb 04 2020

Examples

			k = 5 is here because 4*5! - 1 = 479 is prime.

Crossrefs

Cf. A076680.
Cf. A002982, A076133, A076134, A099351, A180627, A180628, A180629, A180630, A180631.

Programs

  • Maple
    for n from 0 to 1000 do if isprime(4*n! - 1) then print(n) end if end do;
  • Mathematica
    For[n = 0, True, n++, If[PrimeQ[4 n! - 1], Print[n]]] (* Jean-François Alcover, Sep 23 2015 *)
  • PARI
    is_A099350(n)=ispseudoprime(n!*4-1) \\ M. F. Hasler, Sep 20 2015

Extensions

a(14) from Alois P. Heinz, Sep 21 2015
a(15)-a(16) from Jean-François Alcover, Sep 23 2015
a(17)-a(18) from Jinyuan Wang, Feb 04 2020
a(19) from Michael S. Branicky, May 16 2023
a(20)-a(21) from Michael S. Branicky, Jul 11 2024

A076679 Numbers k such that 3*k! + 1 is prime.

Original entry on oeis.org

2, 3, 4, 6, 7, 9, 10, 13, 23, 25, 32, 38, 40, 47, 96, 3442, 4048, 4522, 4887, 7033, 9528, 12915, 31762, 114482
Offset: 1

Views

Author

Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 25 2002

Keywords

Comments

a(25) > 115000. - Serge Batalov, Jun 15 2025

Examples

			k = 6 is here because 3*6! + 1 = 2161 is prime.

Crossrefs

Cf. A002981, A051915, A076680, A076681, A076682, A076683, A178488, A180626, A126896.

Programs

  • PARI
    isok(n) = isprime(3*n! + 1); \\ Michel Marcus, Nov 13 2016
  • PFGW
    ABC2 3*$a!+1
a: from 1 to 1000 // Jinyuan Wang, Feb 05 2020

Extensions

More terms from Serge Batalov, Feb 18 2015
a(20)-a(23) from Roger Karpin, Nov 13 2016
a(24) from Serge Batalov, Jun 15 2025

A126896 Numbers k such that 10*k! + 1 is prime.

Original entry on oeis.org

0, 1, 3, 4, 5, 23, 32, 39, 61, 349, 718, 805, 1025, 1194, 1550, 1774, 3417, 7583
Offset: 1

Views

Author

Parthasarathy Nambi, May 07 2007

Keywords

Comments

a(17) > 2880. - Jinyuan Wang, Feb 05 2020
a(19) > 12000. - Michael S. Branicky, Jul 07 2024

Examples

			k = 4 is a term because 10*4! + 1 = 241 is prime.

Crossrefs

Corresponding primes are in A089764.
Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A178488, A180626.

Programs

  • PARI
    is(k) = ispseudoprime(10*k!+1); \\ Jinyuan Wang, Feb 05 2020

Extensions

a(15)-a(16) from Jinyuan Wang, Feb 05 2020
a(17) from Michael S. Branicky, Apr 16 2023
a(18) from Michael S. Branicky, Jul 07 2024

A076683 Numbers k such that 7*k! + 1 is prime.

Original entry on oeis.org

3, 7, 8, 15, 19, 29, 36, 43, 51, 158, 160, 203, 432, 909, 1235, 3209, 8715, 9707
Offset: 1

Views

Author

Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 25 2002

Keywords

Comments

a(17) > 5830. - Jinyuan Wang, Feb 05 2020
a(19) > 12000. - Michael S. Branicky, Jul 04 2024

Examples

			k = 3 is here because 7*3! + 1 = 43 is prime.

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076681, A076682, A178488, A180626, A126896.

Programs

  • PARI
    is(k) = ispseudoprime(7*k!+1); \\ Jinyuan Wang, Feb 05 2020
  • Python
    from sympy import isprime
from math import factorial
def aupto(m): return [k for k in range(m+1) if isprime(7*factorial(k)+1)]
print(aupto(300)) # Michael S. Branicky, Mar 07 2021

Extensions

a(17)-a(18) from Michael S. Branicky, Jul 04 2024

A178488 Numbers k such that 8*k! + 1 is prime.

Original entry on oeis.org

2, 4, 9, 10, 11, 12, 15, 25, 31, 46, 53, 78, 318, 615, 955, 1646, 2669, 2672, 3515, 7689
Offset: 1

Views

Author

Robert G. Wilson v, Sep 13 2010 and M. F. Hasler, Sep 16 2010

Keywords

Comments

a(20) > 3810. - Jinyuan Wang, Feb 05 2020
a(21) > 12000. - Michael S. Branicky, Jul 03 2024

Links

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A180626, A126896.

Programs

  • Mathematica
    fQ[n_] := PrimeQ[8 n! + 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst
  • PARI
    for(k=1, 999, ispseudoprime(8*k!+1) & print1(k, ", "))
  • PFGW
    ABC2 8*$a!+1
a: from 1 to 1000 // Jinyuan Wang, Feb 05 2020

Extensions

a(16)-a(19) from Jinyuan Wang, Feb 05 2020
a(20) from Michael S. Branicky, Jul 02 2024

A180626 Numbers k such that 9*k! + 1 is prime.

Original entry on oeis.org

2, 6, 7, 10, 13, 15, 24, 29, 33, 44, 98, 300, 548, 942, 1099, 1176, 1632, 1794, 3676, 3768, 4804, 6499, 8049, 8164, 8917, 10270, 11610, 11959
Offset: 1

Views

Author

Robert G. Wilson v, Sep 13 2010

Keywords

Comments

Tested to 4500. - Robert G. Wilson v, Sep 28 2010
a(22) > 5235. - Jinyuan Wang, Feb 05 2020

Links

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076681, A076682, A076683, A178488, A126896.

Programs

  • Mathematica
    fQ[n_] := PrimeQ[9 n! + 1]; k = 0; lst = {}; While[k < 1501, If[ fQ@k, AppendTo[lst, k]; Print@k]; k++ ]; lst
  • PARI
    is(k) = ispseudoprime(9*k!+1); \\ Jinyuan Wang, Feb 05 2020

Extensions

a(17)-a(20) from Robert G. Wilson v, Sep 28 2010
a(21) from Jinyuan Wang, Feb 05 2020
a(22) from Michael S. Branicky, May 27 2023
a(23)-a(28) from Michael S. Branicky, Jul 12 2024

A076682 Numbers k such that 6*k! + 1 is prime.

Original entry on oeis.org

0, 1, 2, 3, 7, 8, 9, 12, 13, 18, 24, 38, 48, 60, 113, 196, 210, 391, 681, 739, 778, 1653, 1778, 1796, 1820, 2391, 2505, 4595, 8937
Offset: 1

Views

Author

Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 25 2002

Keywords

Comments

a(29) > 5800. - Jinyuan Wang, Feb 05 2020
a(30) > 12000. - Michael S. Branicky, Jul 04 2024

Examples

			k = 3 is here because 6*3! + 1 = 37 is prime.

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076681, A076683, A178488, A180626, A126896.

Programs

  • PARI
    is(k) = ispseudoprime(6*k!+1); \\ Jinyuan Wang, Feb 05 2020

Extensions

a(26) inserted by and a(29) from Michael S. Branicky, Jul 03 2024

A076681 Numbers k such that 5*k! + 1 is prime.

Original entry on oeis.org

2, 3, 5, 10, 11, 12, 17, 34, 74, 136, 155, 259, 271, 290, 352, 479, 494, 677, 776, 862, 921, 932, 2211, 3927, 4688, 12567
Offset: 1

Views

Author

Phillip L. Poplin (plpoplin(AT)bellsouth.net), Oct 25 2002

Keywords

Comments

a(26) > 4700. - Jinyuan Wang, Feb 04 2020

Examples

			k = 3 is here because 5*3! + 1 = 31 is prime.

Crossrefs

Cf. A002981, A051915, A076679, A076680, A076682, A076683, A178488, A180626, A126896.

Programs

  • PARI
    is(k) = ispseudoprime(5*k!+1); \\ Jinyuan Wang, Feb 04 2020

Extensions

a(25) from Jinyuan Wang, Feb 04 2020
a(26) from Michael S. Branicky, Jul 03 2024
Showing 1-10 of 12 results. Next

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