A270927 Smallest k such that k*n^m + 1 is prime, case m=4.

1, 1, 2, 1, 18, 1, 6, 3, 6, 7, 46, 5, 10, 3, 8, 1, 16, 2, 28, 1, 2, 7, 16, 1, 24, 12, 10, 1, 10, 2, 6, 7, 26, 1, 12, 3, 6, 3, 8, 16, 10, 3, 22, 16, 2, 1, 6, 1, 36, 3, 6, 3, 16, 1, 18, 1, 8, 12, 16, 10, 12, 31, 2, 10, 22, 2, 36, 21, 40, 6, 12, 18, 6, 1, 6, 7, 10, 2, 18, 1, 2, 1, 22, 2, 12, 18, 6, 1, 18, 1, 58, 3, 12, 7, 24, 2, 16, 3, 16, 6, 6, 7, 46, 25, 2, 1, 12, 7, 18, 12, 46, 3, 12, 5, 10, 3, 48, 1, 16, 2

Offset: 1

Author

Zak Seidov, Mar 26 2016

Keywords

• nonn

Links

• Zak Seidov, Table of n, a(n) for n = 1..10000
• Zak Seidov,20 related sequences.

Crossrefs

Cf. A034693 (m=1), A035092 (m=2), A238847 (m=3).

Programs

Mathematica

With[{m = 4, nn = 120}, Table[SelectFirst[Range@ nn, PrimeQ[# n^m + 1] &], {n, nn}]] (* Michael De Vlieger, Mar 26 2016, Version 10 *)
sk[n_]:=Module[{k=1,c=n^4},While[!PrimeQ[k*c+1],k++];k]; Array[sk,120] (* Harvey P. Dale, Jun 05 2021 *)

PARI

{m=4;for(n=1,10000,k=1;while(!isprime(k*n^m+1),k++);
write("b270927.txt",n" "k))} \\ for b-file - Zak Seidov, Mar 26 2016