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 A290504 Hypotenuses for which there exist exactly 18 distinct integer triangles. 24
 3814697265625, 7629394531250, 11444091796875, 15258789062500, 22888183593750, 26702880859375, 30517578125000, 34332275390625, 41961669921875, 45776367187500, 53405761718750, 61035156250000, 68664550781250, 72479248046875, 80108642578125, 83923339843750 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers whose square is decomposable in 18 different ways into the sum of two nonzero squares: these are those with only one prime divisor of the form 4k+1 with multiplicity eighteen. LINKS Ray Chandler, Table of n, a(n) for n = 1..10000 (first 1000 terms from Hamdi Sahloul) FORMULA Terms are obtained by the product A004144(k)*A002144(p)^18 for k, p > 0 ordered by increasing values. EXAMPLE a(1) = 3814697265625 = 5^18, a(5) = 22888183593750 = 2*3*5^18, a(101) = 732421875000000 = 2^6*3*5^18. MATHEMATICA r[a_]:={b, c}/.{ToRules[Reduce[0

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Last modified May 24 22:09 EDT 2024. Contains 372782 sequences. (Running on oeis4.)