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A226498 The number of primes of the form i^2 + j^4 (A028916) <= 2^n. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

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.

REFERENCES

John Friedlander and Henryk Iwaniec, Using a parity-sensitive sieve to count prime values of a  polynomial, PNAS 94 (4), 1997, pp. 1054-1058.

LINKS

Table of n, a(n) for n=1..36.

MATHEMATICA

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}]

PROG

(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

CROSSREFS

Cf. A028916, A226495, A226496, A226497.

Sequence in context: A214040 A077419 A125189 * A196375 A300440 A147997

Adjacent sequences:  A226495 A226496 A226497 * A226499 A226500 A226501

KEYWORD

nonn

AUTHOR

Marek Wolf) and Robert G. Wilson v, Jun 09 2013

STATUS

approved

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Last modified January 23 04:16 EST 2020. Contains 331168 sequences. (Running on oeis4.)