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A023107 Largest integer in which every prefix is prime in base n (written in base 10). 14
71, 191, 2437, 108863, 6841, 4497359, 1355840309, 73939133, 6774006887, 18704078369, 122311273757, 6525460043032393259, 927920056668659, 16778492037124607, 4928397730238375565449, 5228233855704101657, 3013357583408354653, 1437849529085279949589, 101721177350595997080671, 185720479816277907890970001 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

Or, largest right-truncatable prime with base n>2 (in decimal form).

a(n) <= A094335(n).

LINKS

Martin Renner, Max Alekseyev and Giovanni Resta, Table of n, a(n) for n = 3..100

I. O. Angell, and H. J. Godwin, On Truncatable Primes, Math. Comput. 31, 265-267, 1977.

N. J. A. Sloane, The Angell-Godwin table of initial terms of A023107 and A103443

Eric Weisstein. Truncatable Prime.

Index entries for sequences related to truncatable primes

EXAMPLE

a(100) = 70123916363515199416199518301698321195339012727994799// 190371992151279729974757397909992327936943877127375781091143. - Giovanni Resta, Apr 11 2016

PROG

(PARI) a(n) = my(S, m, D); D=select(x->(gcd(x, n)==1), vector(n-1, j, j)); S=select(ispseudoprime, vector(n-1, i, i)); while(#S, m=vecmax(S); S=concat(vector(#D, j, select(ispseudoprime, vector(#S, i, S[i]*n+D[j])))); ); m /* Max Alekseyev, Dec 09 2014 */

CROSSREFS

Cf. A076586.

Sequence in context: A142612 A139991 A140007 * A174370 A174454 A142808

Adjacent sequences:  A023104 A023105 A023106 * A023108 A023109 A023110

KEYWORD

nonn,base

AUTHOR

David W. Wilson

EXTENSIONS

More terms from Don Reble, Jun 23 2004

a(54)-a(75) in b-file from Max Alekseyev, Dec 09 2014

a(76)-a(100) in b-file from Giovanni Resta, May 01 2016

STATUS

approved

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Last modified March 29 21:48 EDT 2017. Contains 284288 sequences.