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A090788 Numbers that can be expressed as the difference of the squares of primes in just two distinct ways. 24

%I

%S 72,360,432,528,768,888,960,1032,1080,1128,1272,1392,1488,1512,1608,

%T 1632,1728,1920,2088,2112,2232,2352,2400,2448,2568,2688,2808,3048,

%U 3168,3240,3288,3480,3648,3768,4008,4032,4128,4248,4272,4392,4488,4512,4992

%N Numbers that can be expressed as the difference of the squares of primes in just two distinct ways.

%e 72 = 11^2 - 7^2 = 19^2 - 17^2.

%o (PARI) i=4; while(i<=5000, k=0; m=2; while(m*m<=i, if(i%(2*m)==0, a=(i/m-m)/2; b=a+m; if(isprime(a)&&isprime(b), k+=1)); m+=2); if(k==2, print1(i, ", ")); i+=4) \\ _Antonio Roldán_, Nov 06 2018

%Y Cf. A078667, A090781, A090782.

%K nonn

%O 1,1

%A _Ray Chandler_, Feb 14 2004

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Last modified November 21 14:18 EST 2019. Contains 329371 sequences. (Running on oeis4.)