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A182198 Primes of form a^2 + b^2 such that a^4 + b^4 is prime. 2
2, 5, 13, 17, 29, 37, 41, 53, 73, 89, 137, 149, 157, 181, 257, 269, 281, 293, 313, 349, 373, 397, 401, 409, 421, 461, 541, 557, 577, 593, 661, 709, 733, 757, 769, 773, 797, 853, 937, 953, 1021, 1049, 1069, 1181, 1237, 1277, 1301, 1373, 1429, 1433, 1453, 1489 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

13 = 2^2 + 3^2, 2^4 + 3^4 = 97 is prime.

MATHEMATICA

nn = 40; t = {}; Do[c = a^2 + b^2; If[c < nn^2 && PrimeQ[c] && PrimeQ[a^4 + b^4], AppendTo[t, c]], {a, nn}, {b, a}]; Sort[t] (* T. D. Noe, Apr 22 2012 *)

Take[#[[1]]^2+#[[2]]^2&/@Select[Tuples[Range[40], 2], AllTrue[{#[[1]]^2+ #[[2]]^2, #[[1]]^4+#[[2]]^4}, PrimeQ]&]//Union, 60] (* Harvey P. Dale, Jun 25 2018 *)

PROG

(PARI) list(lim)=my(v=List(), t); lim\=1; for(x=1, sqrtint(lim), for(y=1, min(sqrtint(lim-x^2), x), if(isprime(t=x^2+y^2)&&isprime(x^4+y^4), listput(v, t)))); vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, Apr 22 2012

CROSSREFS

Subsequence of A002313.

Cf. A003336 (numbers that are the sum of 2 nonzero 4th powers).

Cf. A002645 (quartan primes: primes of the form x^4 + y^4).

Sequence in context: A086807 A002313 A233346 * A291275 A291278 A177349

Adjacent sequences:  A182195 A182196 A182197 * A182199 A182200 A182201

KEYWORD

nonn

AUTHOR

Thomas Ordowski, Apr 20 2012

STATUS

approved

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Last modified May 28 21:37 EDT 2020. Contains 334690 sequences. (Running on oeis4.)