The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A242553 Least number k such that n^8+k^8 is prime. 1
 1, 1, 10, 1, 6, 5, 12, 13, 16, 3, 24, 7, 2, 3, 8, 9, 4, 17, 4, 7, 2, 3, 20, 7, 8, 19, 10, 3, 10, 19, 14, 17, 32, 11, 8, 25, 6, 25, 40, 7, 10, 43, 16, 5, 68, 7, 30, 5, 8, 19, 58, 17, 26, 17, 2, 11, 10, 3, 4, 49, 6, 71, 22, 15, 14, 47, 30, 9, 2, 19, 6, 19, 6, 5, 28, 13, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS If a(n) = 1, then n is in A006314. LINKS EXAMPLE 10^8+1^8 = 100000001 is not prime. 10^8+2^8 = 100000256 is not prime. 10^8+3^8 = 100006561 is prime. Thus, a(10) = 3. MATHEMATICA lnk[n_]:=Module[{c=n^8, k=1}, While[CompositeQ[c+k^8], k++]; k]; Array[lnk, 80] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 12 2020 *) PROG (Python) import sympy from sympy import isprime def a(n): ..for k in range(10**4): ....if isprime(n**8+k**8): ......return k n = 1 while n < 100: ..print(a(n)) ..n += 1 (PARI) a(n)=for(k=1, 10^3, if(ispseudoprime(n^8+k^8), return(k))); n=1; while(n<100, print(a(n)); n+=1) CROSSREFS Cf. A069003, A006314. Sequence in context: A321097 A015810 A010183 * A113513 A092030 A014538 Adjacent sequences:  A242550 A242551 A242552 * A242554 A242555 A242556 KEYWORD nonn AUTHOR Derek Orr, May 17 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 18 22:45 EDT 2021. Contains 343098 sequences. (Running on oeis4.)