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A292313 Numbers that are the sum of three squares in arithmetic progression. 6

%I

%S 75,300,507,675,867,1200,1875,2028,2523,2700,3468,3675,4107,4563,4800,

%T 5043,6075,7500,7803,8112,8427,9075,10092,10800,11163,12675,13872,

%U 14700,15987,16428,16875,18252,19200,20172,21675,22707,23763,24300,24843,27075,28227,30000,30603

%N Numbers that are the sum of three squares in arithmetic progression.

%H Chai Wah Wu, <a href="/A292313/b292313.txt">Table of n, a(n) for n = 1..10000</a>

%F Sequence is 3*(distinct elements in A198385).

%F Numbers of the form 3*m^2 where 2*m^2 is in A004431. - _Chai Wah Wu_, Oct 05 2017

%e 75 = 1^2 + 5^2 + 7^2 = 1 + 25 + 49, with 25 - 1 = 49 - 25 = 24.

%e 675 = 3^2 + 15^2 + 21^2 = 9 + 225 + 441, with 225 - 9 = 441 - 225 = 216.

%o (PARI) t=4; k=3; while(t<=13000, i=k; e=0; v=t+i; while(i>1&&e==0, if(issquare(v), m=3*t; e=1; print1(m,", ")); i+=-2; v+=i); k+=2; t+=k)

%Y Subsequence of A033428.

%Y Cf. A000290, A000378, A004431, A134422, A292309, A292310, A292314, A292316.

%K nonn

%O 1,1

%A _Antonio Roldán_, Sep 14 2017

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Last modified October 16 01:42 EDT 2019. Contains 328038 sequences. (Running on oeis4.)