This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A253805 a(n) gives one fourth of the even leg of the second of the two Pythagorean triangles with hypotenuse A080109(n) = A002144(n)^2. The odd leg is given in A253804. 3
 5, 30, 34, 145, 111, 180, 371, 330, 876, 1560, 1746, 505, 1635, 840, 3014, 3570, 5181, 2249, 1710, 7980, 1379, 3435, 10920, 7230, 2056, 8970, 14490, 11240, 4981, 3900 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS See A253804 for comments and the Dickson reference. REFERENCES L. E. Dickson, History of the Theory of Numbers, Carnegie Institution, Publ. No. 256, Vol. II, Washington D.C., 1920, p. 227. LINKS FORMULA a(n) = sqrt(A080109(n)^2 - A253804(n)^2)/4, n >= 1. EXAMPLE n = 7: A080175(7) = 7890481 = 53^4 = 2809^2; A002144(7)^4 = A253804(7)^2 + (4*a(7))^2 = 2385^2 + (4*371)^2. The other Pythagorean triangle with hypotenuse 53^2 = 2809 has odd leg A253802(7) = 1241 and even leg 4*A253303(7) = 4*630 = 2520: 53^4 = 1241^2 + (4*630)^2. CROSSREFS Cf. A002144, A080109, A253804, A253802, A253803. Sequence in context: A098346 A134166 A154522 * A222463 A097252 A169610 Adjacent sequences:  A253802 A253803 A253804 * A253806 A253807 A253808 KEYWORD nonn,easy AUTHOR Wolfdieter Lang, Jan 16 2015 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.

Last modified October 15 23:54 EDT 2019. Contains 328038 sequences. (Running on oeis4.)