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Intersection of A154777 and A155717: N = a^2 + 2b^2 = c^2 + 7d^2 for some positive integers a,b,c,d.
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%I #4 Jul 14 2012 11:32:23

%S 11,43,44,67,72,88,99,107,113,121,137,144,163,172,176,179,193,211,233,

%T 268,275,281,288,331,337,344,347,352,379,387,396,401,428,443,449,452,

%U 457,473,484,491,499,536,539,547,548,569,571,576,603,617,641,648,652

%N Intersection of A154777 and A155717: N = a^2 + 2b^2 = c^2 + 7d^2 for some positive integers a,b,c,d.

%o (PARI) isA155711(n,/* optional 2nd arg allows us to get other sequences */c=[7,2]) = { for(i=1,#c, for(b=1,sqrtint((n-1)\c[i]), issquare(n-c[i]*b^2) & next(2)); return);1}

%o for( n=1,999, isA155711(n) & print1(n","))

%Y Cf. A000404, A154777, A092572, A097268, A154778, A155716, A155717, A155560-A155578.

%K easy,nonn

%O 1,1

%A _M. F. Hasler_, Jan 25 2009