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.

A104026 Numbers that can be represented as k^2*j, 0 < j <= k but not if gcd(k, j) = 1.

Original entry on oeis.org

32, 72, 108, 128, 200, 243, 288, 384, 392, 432, 486, 500, 512, 600, 675, 800, 864, 972, 1125, 1152, 1176, 1323, 1350, 1372, 1440, 1536, 1568, 1728, 1944, 1960, 2000, 2048, 2187, 2250, 2400, 2560, 2592, 2646, 2700, 2904, 3087, 3125, 3200, 3240, 3267, 3380
Offset: 1

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Author

Leroy Quet and Robert G. Wilson v, Feb 25 2005

Keywords

Comments

The complement of A104020 and A104021.

Examples

			32 is in the list because 32 = 4^2*2 but gcd(4,2) = 2.
		

Crossrefs

Programs

  • Mathematica
    A104020 = Take[Union[Flatten[Table[k^2 * j, {k, 70}, {j, k - 1}]]], 200]; A104021 = Take[Union[Flatten[Table[If[GCD[k, j] == 1, k^2 * j, {}], {k, 70}, {j, k - 1}]]], 150]; Complement[A104020, A104021]