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A124207 Numbers n such that 1 + n + n^3 + n^5 + n^7 + n^9 + n^11 + ... + n^53 + n^55 is prime. 2
1, 186, 256, 325, 763, 853, 916, 1239, 1297, 1398, 1500, 1669, 1878, 1992, 2373, 2503, 2536, 2578, 2626, 2740, 2823, 2836, 2841, 2926, 2958, 3193, 3255, 3381, 3447, 3738, 3843, 3903, 4095, 4156, 4246, 4321, 4407, 4530, 4540, 4572, 4855, 5190, 5322, 5361, 5530 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..270

MAPLE

a:= proc(n) option remember; local k;

      for k from 1+ a(n-1) while

        not isprime(1+(k^57-k)/(k^2-1)) do od; k

    end: a(1):=1:

seq(a(n), n=1..30);  # 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 + n^41 + n^43 + n^45 + n^47 + n^49 + n^51 + n^53 + n^55], Print[n]], {n, 1, 2400}]

Select[Range[6000], PrimeQ[Total[#^Range[1, 55, 2]] + 1] &] (* Vincenzo Librandi, Jun 28 2014 *)

PROG

(PARI) for(n=1, 10^4, if(ispseudoprime(sum(i=0, 27, n^(2*i+1))+1), print1(n, ", "))) \\ Derek Orr, Jun 24 2014

(MAGMA) [n: n in [0..6000] | IsPrime(s) where s is 1+&+[n^i: i in [1..55 by 2]]]; // Vincenzo Librandi, Jun 28 2014

CROSSREFS

Cf. A049407, similar sequences listed in A244376.

Sequence in context: A015273 A214605 A186398 * A189941 A260923 A151701

Adjacent sequences:  A124204 A124205 A124206 * A124208 A124209 A124210

KEYWORD

nonn,easy

AUTHOR

Artur Jasinski, Dec 13 2006

EXTENSIONS

a(42) and beyond from Derek Orr, Jun 24 2014

STATUS

approved

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Last modified August 4 18:27 EDT 2020. Contains 336202 sequences. (Running on oeis4.)