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 A025317 Numbers that are the sum of 2 distinct nonzero squares in 7 or more ways. 5

%I

%S 27625,32045,40885,45305,47125,55250,58565,60125,61625,64090,66625,

%T 67405,69745,71825,77285,78625,80665,81770,86125,87125,90610,91205,

%U 93925,94250,98345,98605,99125,99905,101065,105625,107185,110500,111605,112625

%N Numbers that are the sum of 2 distinct nonzero squares in 7 or more ways.

%C Subsequence of A025298. But sequences A025317 and A025298 are different. 2*5^12 = 488281250 = 15625^2 + 15625^2 (not distinct squares) = 14395^2 + 16765^2 = 10625^2 + 19375^2 = 9125^2 + 20125^2 = 4775^2 + 21575^2 = 3125^2 + 21875^2 = 1457^2 + 22049^2 is not in A025317. - _Vaclav Kotesovec_, Feb 27 2016

%C Numbers in A025298 but not in A025317 are exactly those numbers of the form 2*p_1^(2*a_1)*p_2^(2*a_2)*...*p_m^(2*a_m)*q^12 where p_i are primes of the form 4k+3 and q is a prime of the form 4k+1. Thus 2*5^12 is the smallest term in A025298 that is not in A025317. - _Chai Wah Wu_, Feb 27 2016

%H Chai Wah Wu, <a href="/A025317/b025317.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Su#ssq">Index entries for sequences related to sums of squares</a>

%t nn = 112625; t = Table[0, {nn}]; lim = Floor[Sqrt[nn - 1]]; Do[num = i^2 + j^2; If[num <= nn, t[[num]]++], {i, lim}, {j, i - 1}]; Flatten[Position[t, _?(# >= 7 &)]] (* _T. D. Noe_, Apr 07 2011 *)

%K nonn

%O 1,1

%A _David W. Wilson_

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Last modified January 21 16:22 EST 2020. Contains 331114 sequences. (Running on oeis4.)