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.

A289554 Numbers that are the product of two distinct composite numbers (A002808).

Original entry on oeis.org

24, 32, 36, 40, 48, 54, 56, 60, 64, 72, 80, 84, 88, 90, 96, 100, 104, 108, 112, 120, 126, 128, 132, 135, 136, 140, 144, 150, 152, 156, 160, 162, 168, 176, 180, 184, 189, 192, 196, 198, 200, 204, 208, 210, 216, 220, 224, 225, 228, 232, 234, 240, 243, 248, 250
Offset: 1

Views

Author

Jaroslav Krizek, Jul 07 2017

Keywords

Examples

			Number 24 is in the sequence because 24 = 4 * 6.
		

Crossrefs

Complement of A289555.
Cf. A006881 (with two distinct primes), A002808 (with two distinct nonprimes), A167171 (with two distinct noncomposites).

Programs

  • Magma
    [n: n in [1..1000] | (#PrimeDivisors(n) eq 1 and NumberOfDivisors(n) ge 6) or (#PrimeDivisors(n) eq 2 and NumberOfDivisors(n) ge 8) or (#PrimeDivisors(n) ge 3 and NumberOfDivisors(n) ge 12) or (#PrimeDivisors(n) ge 4)];