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.

A305888 Numbers that are the perimeter of a Heronian triangle, but not of a primitive Heronian triangle.

Original entry on oeis.org

24, 88, 280, 472, 558, 664, 696, 852, 856, 1048, 1432, 1720, 1816, 2008, 2180, 2292, 2680, 2776, 2868, 3144, 3352, 3544, 3576, 3582, 3732, 3736, 3860, 3928, 4192, 4308, 4504, 4696, 4878, 4976, 5080, 5172, 5272, 5464, 5598, 5748, 6520, 6616, 6740, 6744, 7188
Offset: 1

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Author

Giovanni Resta, Jun 14 2018

Keywords

Comments

Numbers in A051518 that are not in A096468.

Examples

			The only Heronian triangle with perimeter 24 has sides {6, 8, 10} and thus it is not primitive. Hence 24 is in the sequence.
		

Crossrefs

Programs

  • Mathematica
    hpp[p_] := Catch@Block[{t=0, c, q=p/2}, Do[c = p-a-b; If[c >= b && a+c > b && a+b > c && IntegerQ@ Sqrt[q (q-a) (q-b) (q-c)], t++; If[GCD[a, b, c] == 1, Throw@ False]], {a, p/3}, {b, a, p-a-1}]; t > 0]; Select[2 Range[350], hpp]