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 1-3 of 3 results.

A097419 a(1) = 2, a(n) = 2*a(n-1)^2 - a(n-1) for n > 1.

Original entry on oeis.org

2, 6, 66, 8646, 149497986, 44699295486614406, 3996054033999333969062944766851266, 31936895685284700329548847429175178142518023225832967407199564754246
Offset: 1

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Author

Gerald McGarvey, Aug 19 2004

Keywords

Comments

These numbers when factored are 2*3, 2*3*11, 2*3*11*131, 2*3*11*131*17291, 2*3*11*131*17291*298995971, 2*3*11*131*8779*10079*17291*298995971*1010341471, 2*3*11*29*59*131*241*8779*10079*17291*298995971*1010341471*2511683491*7716660340023314591, so a(n) is a prime multiple of a(n-1) for 2<=n<=6. 2,3,11,131,17291,298995971 are A090475 [Beginning with 2, a(n+1) is the least prime == -1 (mod (product a(i), i=1 to n)).]

Crossrefs

Cf. A090475.

A090476 Beginning with 2, a(n+1) is the least prime == -1 (mod (Sum a(i), i=1 to n)).

Original entry on oeis.org

2, 3, 19, 23, 281, 983, 2621, 3931, 62903, 212297, 1698377, 7925759, 99071989, 435916751, 5448959389, 17981565983, 1390574436037, 7072749286739, 50923794864521, 178233282025823, 2851732512413171, 30893768884476019
Offset: 1

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Author

Amarnath Murthy, Dec 02 2003

Keywords

Crossrefs

Extensions

More terms from David Wasserman, Nov 16 2005

A263539 Smallest odd prime of the form k*a(n-1)*a(n-2)*...*a(1) + 2.

Original entry on oeis.org

3, 5, 17, 257, 65537, 73014444017, 7839866227890585600377, 90965983657404652017189201081165598949585237, 59265532390032181385721703100931439246761487956490653915298719426194939212611074425177277
Offset: 1

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Author

Jeppe Stig Nielsen, Oct 20 2015

Keywords

Comments

Infinite sequence of primes which coincides with Fermat primes, a(n) = A019434(n-1), only for n <= 5.
For the k values, see A263540.

Crossrefs

Programs

  • PARI
    terms=12; p=1; for(n=1, terms, q=p+2; while(!ispseudoprime(q), q+=2*p); print1(q, ", "); p*=q)
Showing 1-3 of 3 results.