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.

A090122 Numbers k such that nextprime(k^4) - prevprime(k^4) = 4.

Original entry on oeis.org

2, 3, 21, 34, 46, 87, 99, 129, 141, 220, 242, 254, 266, 278, 279, 476, 526, 550, 616, 627, 657, 772, 777, 783, 795, 1072, 1088, 1322, 1442, 1486, 1540, 1552, 1586, 1653, 1725, 1833, 1959, 1994, 2001, 2043, 2068, 2192, 2224, 2360, 2384, 2432, 2734, 2770, 2866
Offset: 1

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Author

Labos Elemer, Jan 12 2004

Keywords

Examples

			For k = 21: k^4 = 194481, q = nextprime(k^4) = 194483, p = prevprime(k^4) = 194479, q - p = 4, so 21 is in the sequence.
		

Crossrefs

Programs

  • Mathematica
    pre[x_] := Prime[PrimePi[x]]; nex[x_] := Prime[PrimePi[x]+1]; de[x_] := Prime[PrimePi[x]+1]-Prime[PrimePi[x]]; k=4; Do[If[Equal[Prime[PrimePi[n^k]+1]-Prime[PrimePi[n^k]], 4], Print[n]], {n, 2, 100000}]
  • PARI
    is(k) = nextprime(k^4 + 1) - precprime(k^4 - 1) == 4; \\ Amiram Eldar, Jun 09 2024

Extensions

a(29)-a(49) from Giovanni Resta, May 08 2017