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A024409 Hypotenuses of more than one primitive Pythagorean triangle. 11
65, 85, 145, 185, 205, 221, 265, 305, 325, 365, 377, 425, 445, 481, 485, 493, 505, 533, 545, 565, 629, 685, 689, 697, 725, 745, 785, 793, 845, 865, 901, 905, 925, 949, 965, 985, 1025, 1037, 1073, 1105, 1145, 1157, 1165, 1189, 1205, 1241, 1261, 1285, 1313, 1325 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The subsequence allowing 4 different shapes is in A159781. [R. J. Mathar, Apr 12 2010]

A024362(a(n)) > 1. - Reinhard Zumkeller, Dec 02 2012

LINKS

Ray Chandler, Table of n, a(n) for n = 1..10000 (first 1000 terms from Reinhard Zumkeller)

Ron Knott, Pythagorean Triples and Online Calculators

MATHEMATICA

f[c_] := f[c] = Block[{a = 1, b, cnt = 0, lmt = Floor[ Sqrt[c^2/2]]}, While[b = Sqrt[c^2 - a^2]; a < lmt, If[IntegerQ@ b && GCD[a, b, c] == 1, cnt++]; a++]; cnt]Select[1 + 4 Range@ 335, f@# > 1 &] (* Robert G. Wilson v, Mar 16 2014 *)

Select[Tally[Sqrt[Total[#^2]]&/@Union[Sort/@({Times@@#, (Last[#]^2-First[ #]^2)/2}&/@(Select[Subsets[Range[1, 71, 2], {2}], GCD@@# == 1&]))]], #[[2]]> 1&][[All, 1]]//Sort (* Harvey P. Dale, Sep 29 2018 *)

PROG

(Haskell)

import Data.List (findIndices)

a024409 n = a024409_list !! (n-1)

a024409_list = map (+ 1) $ findIndices (> 1) a024362_list

-- Reinhard Zumkeller, Dec 02 2012

CROSSREFS

Cf. A020882, A120960, subsequence of A008846.

Sequence in context: A084648 A224770 A274044 * A131574 A323272 A322781

Adjacent sequences:  A024406 A024407 A024408 * A024410 A024411 A024412

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified December 2 18:08 EST 2020. Contains 338887 sequences. (Running on oeis4.)