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A226498
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The number of primes of the form i^2 + j^4 (A028916) <= 2^n.
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3
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1, 1, 2, 2, 3, 5, 7, 11, 17, 28, 43, 67, 108, 173, 272, 434, 690, 1115, 1772, 2815, 4528, 7267, 11646, 18799, 30378, 48956, 79270, 128267, 208509, 338533, 550262, 895284, 1457111, 2374753, 3874445, 6327042
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OFFSET
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1,3
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COMMENTS
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Iwaniec and Friedlander proved there are infinity of the primes of the form i^2+j^4, and hence a(n) increases without bound.
Does not count double representations.
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LINKS
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MATHEMATICA
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mx = 2^40; lst = {}; Do[a = i^2 + j^4; If[ PrimeQ[a], AppendTo[lst, a]], {i, Sqrt[mx]}, {j, Sqrt[ Sqrt[mx - i^2]]}]; Table[ Length@ Select[ Union@ lst, # < 2^n &], {n, 40}]
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PROG
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(PARI) a(n)=my(N=2^n, v=List(), t); for(a=1, sqrt(N), forstep(b=a%2+1, sqrtint(sqrtint(N-a^2)), 2, t=a^2+b^4; if(isprime(t), listput(v, t)))); 1+#vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, Jun 12 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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