A124189 Numbers n such that 1 + n + n^3 + n^5 + n^7 + n^9 + n^11 + ... + n^37 + n^39 is prime.

42, 47, 60, 119, 153, 179, 195, 236, 269, 287, 383, 821, 846, 921, 924, 1104, 1181, 1200, 1349, 1806, 1917, 1980, 2015, 2049, 2057, 2369, 2394, 2522, 2660, 2876, 2882, 2940, 2991, 3206, 3311, 3570, 3695, 3741, 3785, 3840, 3944, 3966, 4049, 4148, 4377, 4448

Offset: 1

Author

Artur Jasinski, Dec 13 2006

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..195

Crossrefs

Cf. A049407.

Programs

Magma

[n: n in [0..4000] | IsPrime(s) where s is 1+&+[n^i: i in [1..39 by 2]]]; // Vincenzo Librandi, Nov 12 2010, revised Jun 27 2014

Maple

a:= proc(n) option remember; local k;
      for k from 1 +`if`(n=1, 1, a(n-1)) while
        not isprime(1+(k^41-k)/(k^2-1)) do od; k
    end:
seq(a(n), n=1..40);  # Alois P. Heinz, Jun 26 2014

Mathematica

Do[If[PrimeQ[1+n+n^3+n^5+n^7+n^9+n^11+n^13+n^15+n^17+n^19 +n^21 +n^23 +n^25 +n^27+n^29+n^31+ n^33+n^35+n^37+n^39],Print[n]],{n,1,2400}]
Select[Range[5000], PrimeQ[Total[#^Range[1, 39, 2]] + 1] &] (* Vincenzo Librandi, Jun 27 2014 *)

PARI

for(n=1, 10^4, if(ispseudoprime(sum(i=0, 19, n^(2*i+1))+1), print1(n,", "))) \\ Derek Orr, Jun 24 2014

Extensions

a(43) and beyond from Derek Orr, Jun 24 2014