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A003618 Largest n-digit prime.
(Formerly M4452)
34
7, 97, 997, 9973, 99991, 999983, 9999991, 99999989, 999999937, 9999999967, 99999999977, 999999999989, 9999999999971, 99999999999973, 999999999999989, 9999999999999937, 99999999999999997, 999999999999999989, 9999999999999999961 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

O'Hara, J. Rec. Math., 22 (1990), Table on page 278.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n=1..200 [Jon E. Schoenfield verified that these numbers are indeed all primes, Feb 02 2009]

Eric Weisstein's World of Mathematics, Previous Prime

MATHEMATICA

Table[a := 10^(n + 1); While[ ! PrimeQ[a], a-- ]; a, {n, 0, 30}] (* Stefan Steinerberger, Apr 08 2006 *)

NextPrime[#, -1]&/@(10^Range[20])  (* Harvey P. Dale, Feb 03 2011 *)

PROG

(PARI) a(n)=precprime(10^n) \\ Charles R Greathouse IV, Jul 19 2011

(MAGMA) [PreviousPrime(10^n): n in [1..20]]; // Vincenzo Librandi, Sep 13 2016

CROSSREFS

Cf. A003617, A033874.

Sequence in context: A125590 A068694 A158579 * A173833 A093172 A074110

Adjacent sequences:  A003615 A003616 A003617 * A003619 A003620 A003621

KEYWORD

nonn,nice,base

AUTHOR

N. J. A. Sloane, Mira Bernstein

EXTENSIONS

More terms from Stefan Steinerberger, Apr 08 2006

STATUS

approved

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Last modified May 25 15:52 EDT 2017. Contains 287039 sequences.