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A025314 Numbers that are the sum of 2 distinct nonzero squares in 4 or more ways. 5

%I #22 Feb 28 2016 03:04:36

%S 1105,1625,1885,2125,2210,2405,2465,2665,3145,3250,3445,3485,3625,

%T 3770,3965,4225,4250,4420,4505,4625,4745,4810,4930,5125,5185,5330,

%U 5365,5525,5785,5945,6205,6290,6305,6409,6500,6565,6625,6890,6970,7085,7225,7250

%N Numbers that are the sum of 2 distinct nonzero squares in 4 or more ways.

%C Subsequence of A025295. But sequences A025295 and A025314 are different, A025295(346) = 31250 = 175^2 + 25^2 = 161^2 + 73^2 = 155^2 + 85^2 = 125^2 + 125^2 (not distinct squares) is not in A025314. - _Vaclav Kotesovec_, Feb 27 2016

%C Numbers in A025295 but not in A025314 are exactly those numbers of the form 2*p_1^(2*a_1)*p_2^(2*a_2)*...*p_m^(2*a_m)*q^6 where p_i are primes of the form 4k+3 and q is a prime of the form 4k+1. Thus 2*5^6 = 31250 is the smallest term in A025295 that is not in A025314. - _Chai Wah Wu_, Feb 27 2016

%H Vaclav Kotesovec, <a href="/A025314/b025314.txt">Table of n, a(n) for n = 1..1500</a>

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

%t nn = 7250; 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, _?(# >= 4 &)]] (* _T. D. Noe_, Apr 07 2011 *)

%K nonn

%O 1,1

%A _David W. Wilson_

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Last modified April 17 21:22 EDT 2024. Contains 371767 sequences. (Running on oeis4.)