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A146945 Hypotenuses of primitive Pythagorean triples which are not prime numbers and which are the hypotenuse of a unique triangle. 5
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; text; internal format)
OFFSET
1,1
COMMENTS
Each term is a prime power of the form p^e where p is in A002144 and e>1.
A proper subset of A120960 by eliminating A002144.
A proper subset of A120961 by eliminating A024409.
A proper subset of A008846 by eliminating A002144 and A024409.
A proper subset of A020882 by eliminating A002144, A024409 and duplicate entries.
LINKS
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] (* Robert G. Wilson v, May 02 2009 *)
CROSSREFS
Sequence in context: A280390 A225388 A369563 * A044357 A044738 A062672
KEYWORD
nonn
AUTHOR
John Harrison (harrison_uk_2000(AT)yahoo.co.uk), Apr 20 2009
EXTENSIONS
a(7) corrected by and a(17) and further terms from Robert G. Wilson v, May 02 2009
Minor edits to comments. - Ray Chandler, Nov 27 2019
STATUS
approved

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Last modified February 26 06:43 EST 2024. Contains 370335 sequences. (Running on oeis4.)