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.

A152769 Numbers n such that pi(n) is nonprime.

Original entry on oeis.org

1, 2, 7, 8, 9, 10, 13, 14, 15, 16, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 37, 38, 39, 40, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 61, 62, 63, 64, 65, 66, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99
Offset: 1

Views

Author

Omar E. Pol, Dec 18 2008

Keywords

Comments

A000720(n) is nonprime.
Complement of A048989.

Crossrefs

Programs

  • Mathematica
    Select[Range[100],!PrimeQ[PrimePi[#]]&] (* Harvey P. Dale, May 06 2019 *)

Extensions

Edited by N. J. A. Sloane, Dec 19 2008