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A146945
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Hypotenuses of primitive pythagorean triples which are not prime numbers and which are the hypotenuse of a unique triangle.
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1
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25, 125, 169, 289, 625, 841, 1369, 1681, 2197, 2809, 3125, 3721, 4913, 5329, 7921, 9409, 10201, 11881, 12769, 15625, 18769, 22201, 24389, 24649, 28561, 29929, 32761, 37249, 38809, 50653, 52441, 54289, 58081, 66049, 68921, 72361, 76729, 78125
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The terms shown (up to 9409) are all powers of a single prime.
A proper subset of A020882 by eliminating composites and multiples. [From Robert G. Wilson v (rgwv(AT)rgwv.com), May 02 2009]
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MATHEMATICA
| lst1 = {1, 1}; lst2 = {}; Do[ If[ GCD[m, n] == 1, a = 2m*n; b = m^2 - n^2; c = m^2 + n^2; If[ !PrimeQ@c, AppendTo[lst1, c]]], {m, 3, 1000}, {n, If[OddQ@m, 2, 1], m - 1, 2}]; lst1 = Sort@ lst1; Do[ If[ lst1[[n - 1]] != lst1[[n]] && lst1[[n]] != lst1[[n + 1]], AppendTo[lst2, lst1[[n]]]], {n, 2, Length@ lst1 - 1}]; Take[lst2, 50] [From Robert G. Wilson v (rgwv(AT)rgwv.com), May 02 2009]
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CROSSREFS
| Sequence in context: A030081 A075047 A172047 * A044357 A044738 A062672
Adjacent sequences: A146942 A146943 A146944 * A146946 A146947 A146948
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KEYWORD
| nonn
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AUTHOR
| John Harrison (harrison_uk_2000(AT)yahoo.co.uk), Apr 20 2009
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EXTENSIONS
| a(7) corrected by and a(17) and further terms from Robert G. Wilson v (rgwv(AT)rgwv.com), May 02 2009
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