

A198439


Square root of first term of a triple of squares in arithmetic progression that is not a multiple of another triple in (A198384, A198385, A198386).


6



1, 7, 7, 17, 1, 23, 31, 49, 17, 47, 23, 71, 7, 41, 41, 79, 97, 7, 31, 73, 127, 119, 89, 17, 161, 47, 113, 167, 119, 1, 199, 49, 73, 103, 161, 223, 241, 23, 31, 103, 89, 191, 287, 151, 217, 287, 137, 233, 71, 337, 79, 137, 17, 281, 359, 391, 49, 113, 119, 217
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OFFSET

1,2


COMMENTS

A198435(n) = a(n)^2; a(n) = A198388(A198409(n)).
This sequence gives the values xy of primitive Pythagorean triangles (x,y,z) with even y ordered according to the nondecreasing values of the leg sums x+y (called w in the Zumkeller link, and given in A198441). For the equivalence to primitive Pythagorean triples with even y see a comment in A198441.  Wolfdieter Lang, May 22 2013


LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000
Reinhard Zumkeller, Table of initial values
Keith Conrad, Arithmetic progressions of three squares


EXAMPLE

From Wolfdieter Lang, May 22 2013 (Start)
Primitive Pythagorean triple (x,y,z), y even, connection:
a(2) = 7 because the triple with second smallest leg sum x+y = 17 = A198441(2) is (5,12,13), and x  y = y  x = 12  5 = 7.
a(3) = 7 because x + y = A198441(3) = 23, (x,y,z) = (15,8,17) (the primitive triple with third smallest leg sum), and xy = x  y = 15  8 = 7.
(end)


PROG

(Haskell)
a198439 n = a198439_list !! (n1)
a198439_list = map a198388 a198409_list


CROSSREFS

Sequence in context: A168411 A120682 A152910 * A100635 A292084 A168458
Adjacent sequences: A198436 A198437 A198438 * A198440 A198441 A198442


KEYWORD

nonn


AUTHOR

Reinhard Zumkeller, Oct 25 2011


STATUS

approved



