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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A081962 Ordered semiperimeters of primitive Pythagorean triangles with an even short leg (or an odd long leg). 1
20, 35, 42, 63, 72, 88, 99, 110, 130, 143, 156, 165, 195, 210, 221, 238, 255, 266, 272, 285, 304, 323, 336, 342, 357, 391, 399, 414, 420, 437, 450, 460, 475, 483, 506, 525, 540, 550, 575, 594, 600, 609, 621, 638, 667, 675, 682, 696, 702, 713, 725, 744, 754 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If m and n are the generators of the primitive Pythagorean triples (PPT) with m>n, GCD(m,n)=1 and (m+n) odd then the odd leg is m^2-n^2 and the even leg is 2m*n. Therefore the even leg is shortest if 2m*n<m^2-n^2, i.e., m>(1+sqrt(2))*n. Also this is a sequence of numbers whose square is the semiperimeter of a PPT. - Frank M Jackson, Oct 10 2014

LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000 (first 1621 terms from Vincenzo Librandi)

MATHEMATICA

lst1 = {}; Do[If[GCD[m, n]==1&&m(Sqrt[2]+1)<n&&OddQ[m+n], AppendTo[lst1, n(m+n)]],  {n, 1, 100}, {m, 1, n}]; Sort@lst1 (* Frank M Jackson, Oct 10 2014 *)

CROSSREFS

Sequence in context: A325603 A024747 A328051 * A024755 A048022 A255349

Adjacent sequences:  A081959 A081960 A081961 * A081963 A081964 A081965

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Apr 23 2003

EXTENSIONS

More terms from Ray Chandler, Oct 29 2003

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 December 2 09:52 EST 2020. Contains 338876 sequences. (Running on oeis4.)