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A145852 Primes of the form k followed by a 0 and k 9's. 1
109, 2099, 409999, 1909999999999999999999, 2809999999999999999999999999999, 41099999999999999999999999999999999999999999, 7609999999999999999999999999999999999999999999999999999999999999999999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form k*10^(k+1) + 10^k - 1.

LINKS

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

PROG

(PARI) lista(nn) = for(k=1, nn, if(ispseudoprime(q=k*10^(k+1)+10^k-1), print1(q, ", "))); \\ Jinyuan Wang, Mar 24 2020

CROSSREFS

Cf. A141311, A145851.

Sequence in context: A232118 A201849 A061724 * A232198 A232416 A333116

Adjacent sequences:  A145849 A145850 A145851 * A145853 A145854 A145855

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Oct 21 2008

STATUS

approved

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Last modified June 13 07:19 EDT 2021. Contains 344981 sequences. (Running on oeis4.)