This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
Table[Cyclotomic[Prime[n]^2, 2], {n, 7}] (* Arkadiusz Wesolowski, May 13 2012 *)
Table[(2^Prime[n]^2-1)/(2^Prime[n]-1),{n,10}] (* Harvey P. Dale, Apr 06 2019 *)
a:=n->(2^(n^2)-1)/(2^n-1): seq(a(n),n=1..13);
f[n_] := (2^(n^2) - 1)/(2^n - 1); Array[f, 12]
F[n_] := Plus @@ Table[2^((n - i)*n), {i, 1, n}] (* Enrique Pérez Herrero, Feb 23 2009 *)
Table[(2^(n^2) - 1)/(2^n - 1), {n, 1, 20}] (* Vincenzo Librandi, Feb 18 2014 *)
a(n)=(2^n^2-1)/(2^n-1) \\ Charles R Greathouse IV, Feb 17 2014
4 is a term because cyclotomic(4,16) = 1 + 16^2 = 257 is prime.
Do[s=Cyclotomic[n, 2^n]; If[PrimeQ[s], Print[n]], {n, 1, 1000}]
Select[Range[150],PrimeQ[Cyclotomic[#,2^#]]&] (* Harvey P. Dale, Aug 12 2023 *)
isok(k) = isprime(polcyclo(k, 2^k)); \\ Michel Marcus, Dec 17 2020
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