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.

A104080 Smallest prime >= 2^n.

Original entry on oeis.org

2, 2, 5, 11, 17, 37, 67, 131, 257, 521, 1031, 2053, 4099, 8209, 16411, 32771, 65537, 131101, 262147, 524309, 1048583, 2097169, 4194319, 8388617, 16777259, 33554467, 67108879, 134217757, 268435459, 536870923, 1073741827, 2147483659
Offset: 0

Views

Author

Cino Hilliard, Mar 03 2005

Keywords

Crossrefs

Except initial terms and offset, same as A014210 and A203074.
The opposite (greatest prime <= 2^n) is A014234, indices A007053.
The distance from 2^n is A092131, opposite A013603.
Counting zeros instead of both bits gives A372474, cf. A035103, A211997.
Counting ones instead of both bits gives A372517, cf. A014499, A061712.
For squarefree instead of prime we have A372683, cf. A143658, A372540.
The indices of these prime are given by A372684.

Programs

Formula

a(n) = A014210(n), n <> 1. - R. J. Mathar, Oct 14 2008
Sum_{n >= 0} 1/a(n) = A338475 + 1/6 = 1.4070738... (because 1/6 = 1/2 - 1/3). - Bernard Schott, Nov 01 2020
From Gus Wiseman, Jun 03 2024: (Start)
a(n) = A007918(2^n).
a(n) = 2^n + A092131(n).
a(n) = prime(A372684(n)).
(End)

A104082 Smallest prime >= 4^n.

Original entry on oeis.org

2, 5, 17, 67, 257, 1031, 4099, 16411, 65537, 262147, 1048583, 4194319, 16777259, 67108879, 268435459, 1073741827, 4294967311, 17179869209, 68719476767, 274877906951, 1099511627791, 4398046511119, 17592186044423, 70368744177679, 281474976710677, 1125899906842679
Offset: 0

Views

Author

Cino Hilliard, Mar 03 2005

Keywords

Crossrefs

Cf. A104080 (for 2^n), A104081 (for 3^n).
Cf. A014210.

Programs

Formula

a(n) = A104080(2n). - Jinyuan Wang, Nov 09 2018

A340959 Table read by antidiagonals of the smallest prime >= n^k, n >= 1 and k >= 0.

Original entry on oeis.org

2, 2, 2, 2, 2, 2, 2, 3, 5, 2, 2, 5, 11, 11, 2, 2, 5, 17, 29, 17, 2, 2, 7, 29, 67, 83, 37, 2, 2, 7, 37, 127, 257, 251, 67, 2, 2, 11, 53, 223, 631, 1031, 733, 131, 2, 2, 11, 67, 347, 1297, 3137, 4099, 2203, 257, 2, 2, 11, 83, 521, 2411, 7789, 15629, 16411, 6563
Offset: 1

Views

Author

Donald S. McDonald, Jan 31 2021

Keywords

Examples

			Table begins:
  2, 2,  2,   2,   2,    2, ...
  2, 2,  5,  11,  17,   37, ...
  2, 3, 11,  29,  83,  251, ...
  2, 5, 17,  67, 257, 1031, ...
  2, 5, 29, 127, 631, 3137, ...
  ...;
yielding the triangle:
  2;
  2, 2;
  2, 2,  2;
  2, 3,  5,  2;
  2, 5, 11, 11,  2;
  2, 5, 17, 29, 17, 2;
  ...
		

Crossrefs

Cf. A104080 (n=2), A104081 (n=3), A104082 (n=4), A104083 (n=5), A104084 (n=7).

Programs

  • Mathematica
    T[n_,k_]:=NextPrime[n^k-1];Flatten[Table[T[n-k,k],{n,11},{k,0,n-1}]] (* Stefano Spezia, Feb 01 2021 *)
  • PARI
    T(n,k) = nextprime(n^k); \\ Michel Marcus, Feb 01 2021

Formula

T(n,k) = next_prime(n^k-1).
Showing 1-3 of 3 results.