login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A020890 Ordered set of (b + c - a)/2 as (a,b,c) runs through all primitive Pythagorean triples with a < b < c. 3
3, 10, 12, 15, 21, 30, 35, 36, 40, 44, 52, 55, 56, 63, 65, 70, 77, 78, 85, 90, 99, 102, 105, 114, 117, 119, 126, 132, 133, 136, 143, 152, 154, 161, 165, 168, 171, 176, 182, 184, 187, 195, 198, 200, 207, 208, 210, 216, 221, 225, 230, 234, 240, 247, 253, 255, 260, 261, 270 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

From Bernard Schott, May 06 2021: (Start)

Also, ordered sides b of primitive triples (a, b, c) for integer-sided triangles where side a is the harmonic mean of the 2 other sides b and c, i.e., 2/a = 1/b + 1/c with b < a < c (A343892).

The first term appearing twice is 330 = a(71) = a(72). (End)

LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A020889(n)/2.

CROSSREFS

Cf. A020889.

Cf. Triangles with 2/a = 1/b + 1/c:  A343891 (triples), A020883 (side a), A343892 (side b), A343893 (side c), A343894 (perimeter).

Sequence in context: A020681 A283770 A088338 * A343892 A317671 A031453

Adjacent sequences:  A020887 A020888 A020889 * A020891 A020892 A020893

KEYWORD

nonn,changed

AUTHOR

Clark Kimberling

EXTENSIONS

Offset corrected to 1 by Ray Chandler, Jan 23 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 12 06:30 EDT 2021. Contains 343814 sequences. (Running on oeis4.)