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A183186 Numbers n such that 10^(2n+1)-4*10^n-1 is prime. 1
88, 112, 198, 622, 4228, 10052, 55862 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.

LINKS

Table of n, a(n) for n=1..7.

Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's)

Makoto Kamada, Prime numbers of the form 99...99599...99

Index entries for primes involving repunits.

FORMULA

a(n) = (A077786(n)-1)/2.

MATHEMATICA

Do[If[PrimeQ[10^(2n + 1) - 4*10^n - 1], Print[n]], {n, 3000}]

PROG

(PARI) is(n)=ispseudoprime(10^(2*n+1)-4*10^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A115073, A183174-A183187.

Sequence in context: A215830 A216873 A114166 * A161194 A196581 A179245

Adjacent sequences:  A183183 A183184 A183185 * A183187 A183188 A183189

KEYWORD

nonn,base

AUTHOR

Ray Chandler, Dec 28 2010

STATUS

approved

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Last modified October 17 10:43 EDT 2017. Contains 293469 sequences.