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A329392 Ordered perimeters p of primitive Pythagorean triangles no side of which is squarefree. 0
286, 1026, 1702, 1798, 3286, 3920, 4508, 5368, 6042, 6450, 6466, 6552, 7686, 7938, 8520, 8964, 9900, 10044, 10296, 10324, 10494, 11988, 13206, 13612, 13786, 13806, 14058, 14606, 15004, 15912, 16692, 17316, 18382, 18748, 20002, 20328, 21054, 22042, 23074, 24402, 24926, 25500, 25872, 26378, 27104 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are no perimeters p of primitive Pythagorean triangles all sides of which are squarefree. This is because one side is twice the product of two relatively prime numbers not both odd and therefore even.

Many terms of this sequence can be obtained by scaling (3,4,5) the sides of the smallest primitive Pythagorean triangle. For example, a(1) = (3*39) + (4*11) + (5*25).

a(6) is the first term of the sequence which cannot be obtained by scaling (3,4,5). In fact there is no primitive Pythagorean triangle smaller than a(6) that can be scaled to a(6) in the manner above, and in the context of this sequence a(6) can be thought of as "primitive".

a(514) = 310464 is the smallest perimeter corresponding to two triangles, namely (3^2*7^2*263, 2^6*11*89, 5^2*5273) and (2^6*3^2*251, 7^2*11*37, 5*17^2*101). - Giovanni Resta, Nov 15 2019

a(n) is the inner product of two vectors the components of which are relatively prime.

LINKS

Table of n, a(n) for n=1..45.

EXAMPLE

286 is a term because 286 = (2*2*11) + (3*3*13) + (5*5*5).

1026 is a term because 1026 = (3*3*3*11) + (2*2*2*2*19) + (5*5*17).

1702 is a term because 1702 = (3*3*37) + (2*2*7*23) + (5*5*29).

CROSSREFS

Subset of A024364.

Sequence in context: A025384 A256000 A253329 * A253322 A241616 A204035

Adjacent sequences:  A329389 A329390 A329391 * A329393 A329394 A329395

KEYWORD

nonn

AUTHOR

Torlach Rush, Nov 12 2019

STATUS

approved

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Last modified May 18 23:31 EDT 2022. Contains 353826 sequences. (Running on oeis4.)