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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 Cf. A069003, A000068. Sequence in context: A060145 A257806 A035391 * A249717 A249718 A244518 Adjacent sequences:  A242549 A242550 A242551 * A242553 A242554 A242555 KEYWORD nonn AUTHOR Derek Orr, May 17 2014 STATUS approved

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Last modified January 29 01:54 EST 2020. Contains 331328 sequences. (Running on oeis4.)