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A174177 Numbers n such that 10^n-2*n-1 is prime 2
1, 5, 11, 14, 19, 55, 101, 560, 805, 3188, 4441, 25733, 37501 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(14) > 10^5. - Robert Price, Mar 13 2015

LINKS

Table of n, a(n) for n=1..13.

MATHEMATICA

Select[Range[5000], PrimeQ[(10^# - 2*# - 1)] &] (* Vincenzo Librandi, Oct 05 2012 *)

PROG

(MAGMA) [n: n in [1..550] | IsPrime(10^n-2*n-1) ]

(PARI) for(n=1, 999, ispseudoprime(10^n-2*n-1) && print1(n", "))  \\  M. F. Hasler, Aug 06 2011

CROSSREFS

Cf. A173839.

Cf. A110065, A110066, A110067, A173837, A174176.

Sequence in context: A313996 A313997 A313998 * A256785 A084864 A284396

Adjacent sequences:  A174174 A174175 A174176 * A174178 A174179 A174180

KEYWORD

nonn

AUTHOR

Vincenzo Librandi, Mar 11 2010

EXTENSIONS

a(10)-a(11) from Vincenzo Librandi, Oct 05 2012

a(12)-a(13) from Robert Price, Mar 13 2015

STATUS

approved

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Last modified July 16 04:26 EDT 2019. Contains 325064 sequences. (Running on oeis4.)