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A177150
Numbers k such that k^2 + prime(k)^2 is a prime.
1
1, 2, 10, 20, 30, 34, 36, 50, 60, 100, 108, 110, 112, 114, 122, 130, 156, 188, 192, 198, 204, 208, 210, 216, 230, 234, 240, 246, 250, 260, 286, 290, 294, 300, 330, 332, 338, 342, 360, 388, 390, 392, 410, 416, 440, 460, 468, 484, 492, 502, 532, 542, 556, 570
OFFSET
1,2
LINKS
EXAMPLE
100 is in the sequence because the 100th prime is 541, and 100^2 + 541^2 = 302681 is prime.
MAPLE
with(numtheory): nn:= 150: T:=array(1..nn):k:=1:for n from 1 to 1764 do:p:=ithprime(n):if type(p^2+n^2, prime)=true then T[k]:=n:k:=k+1: else fi:od:print(T):
MATHEMATICA
Select[Range[600], PrimeQ[#^2 + Prime[#]^2] &] (* Amiram Eldar, Aug 11 2019 *)
PROG
(Magma) [m:m in [1..600] | IsPrime(m^2+NthPrime(m)^2)]; // Marius A. Burtea, Aug 11 2019
CROSSREFS
Cf. A106587.
Sequence in context: A293725 A351552 A305448 * A165551 A139592 A294544
KEYWORD
nonn
AUTHOR
Michel Lagneau, May 03 2010
STATUS
approved