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A177087 Semiprimes of the form n^5-n^3-2*n^2+1. 1
2951, 16367, 58159, 159479, 368759, 534689, 1414367, 2468519, 3191201, 11862449, 14327767, 20485079, 28597439, 45393809, 102332801, 115783919, 130613617, 146925239, 282352799, 312370001, 344887399, 418040999, 459001729 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
2951=5^5-5^3-2*5^2+1 is in the sequence because 2951=13*227 and 13, 227 are primes;
58159=9^5-9^3-2*9^2+1 is in the sequence because 58159=19*3061 and 19, 3061 are primes, etc.
MATHEMATICA
f[n_] := Last/@FactorInteger[n] == {1, 1}; Select[Array[#^5 - #^3 - 2*#^2 + 1 &, 100], f[#] &] (* Vincenzo Librandi, Sep 21 2012 *)
Select[Table[n^5 - n^3 - 2 n^2 + 1, {n, 60}], PrimeOmega[#] == 2 &] (* Bruno Berselli, Sep 21 2012 *)
PROG
(Magma) IsSemiprime:=func<n | &+[d[2]: d in Factorization(n)] eq 2>; [s: n in [2..60] | IsSemiprime(s) where s is n^5-n^3-2*n^2+1]; // Bruno Berselli, Sep 21 2012
CROSSREFS
Cf. A177075, A177076, A177088 (associated n).
Sequence in context: A259999 A096628 A051024 * A125907 A025514 A204393
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jun 05 2010
EXTENSIONS
Checked by Jud McCranie, Jun 16 2010
STATUS
approved

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Last modified June 18 07:11 EDT 2024. Contains 373469 sequences. (Running on oeis4.)