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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.

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A367103 Composite numbers c such that pi(c) is the product of pi applied to the distinct prime factors of c.

Original entry on oeis.org

15, 21, 39, 57, 65, 91, 95, 133
Offset: 1

Views

Author

Tanya Khovanova, Nov 04 2023

Keywords

Comments

Prime numbers trivially satisfy this property and so are excluded.

Examples

			15 is a term since its distinct prime factors are 3,5 and pi(15) = pi(3)*pi(5).

Crossrefs

Cf. A000720, A002808, A027748, A156061, A235623.

Programs

  • Mathematica
    Select[Range[2,10000], ! PrimeQ[#] && Times @@ PrimePi[Transpose[FactorInteger[#]][[1]]] == PrimePi[#] &]
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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