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A174176 Numbers n such that 10^n-2*n+1 is prime. 5
2, 5, 14, 42, 72, 74, 354, 1176, 1274, 4815, 6885, 28214 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(13) > 10^5. - Robert Price, Mar 26 2015
LINKS
MATHEMATICA
Select[Range[5000], PrimeQ[(10^# - 2 # + 1)] &] (* Vincenzo Librandi, Oct 05 2012 *)
PROG
(Magma) /* The code gives only the terms up to 354: */ [n: n in [1..600] | IsPrime(10^n-2*n+1) ]
(PARI) is(n)=ispseudoprime(10^n-2*n+1) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
Sequence in context: A000660 A148325 A281594 * A298367 A025274 A132833
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Mar 11 2010
EXTENSIONS
a(8)-a(10) from Vincenzo Librandi, Oct 05 2012
a(11)-a(12) from Robert Price, Mar 26 2015
STATUS
approved

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Last modified March 29 06:15 EDT 2024. Contains 371265 sequences. (Running on oeis4.)