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A242552 Least number k such that n^4+k^4 is prime. 0
1, 1, 2, 1, 2, 1, 2, 3, 2, 7, 2, 13, 4, 5, 8, 1, 2, 5, 2, 1, 10, 15, 2, 1, 6, 3, 2, 1, 12, 7, 12, 5, 14, 1, 6, 7, 2, 3, 14, 9, 2, 5, 10, 21, 2, 1, 4, 1, 2, 7, 2, 11, 6, 1, 14, 1, 2, 7, 2, 11, 2, 11, 8, 23, 16, 29, 12, 3, 10, 27, 2, 5, 8, 1, 8, 3, 20, 17, 2, 1, 10, 1, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
If a(n) = 1, then n is in A000068.
LINKS
EXAMPLE
8^4+1^4 = 4097 is not prime. 8^4+2^4 = 4112 is not prime. 8^4+3^4 = 4177 is prime. Thus, a(8) = 3.
PROG
(Python)
import sympy
from sympy import isprime
def a(n):
..for k in range(10**4):
....if isprime(n**4+k**4):
......return k
n = 1
while n < 100:
..print(a(n))
..n += 1
(PARI) a(n)=for(k=1, 10^3, if(ispseudoprime(n^4+k^4), return(k)));
n=1; while(n<100, print(a(n)); n+=1)
CROSSREFS
Sequence in context: A358997 A257806 A035391 * A249717 A249718 A244518
KEYWORD
nonn
AUTHOR
Derek Orr, May 17 2014
STATUS
approved

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Last modified March 3 17:50 EST 2024. Contains 370512 sequences. (Running on oeis4.)