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A094335 Largest right-truncatable prime number in base n if 1 is considered as a prime (written in base 10). 3
47, 71, 2039, 2437, 108863, 33487, 4497359, 1355840309, 1979339339, 6774006887, 2081628860747539, 122311273757, 6525460043032393259, 927920056668659, 1429175974256442233, 4928397730238375565449, 5228233855704101657 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Max Alekseyev, Table of n, a(n) for n = 2..75

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

Domingo Gómez-Pérez, Alina Ostafe, Min Sha, The Arithmetic of Consecutive Polynomial Sequences over Finite Fields, arXiv:1509.01936 [math.NT], 2015.

A. J. van der Poorten, A quote, Math. Intelligencer 7(2) (1985), 40.

Index entries for sequences related to truncatable primes

EXAMPLE

Example for n=10: 1,19,197,1979,19793,197933,1979339,19793393,197933933 and 1979339339 are all prime numbers.

PROG

(PARI) a(n) = my(S, m, D); D=select(x->(gcd(x, n)==1), vector(n-1, j, j)); S=concat([1], select(ispseudoprime, vector(n, j, j))); while(#S, m=vecmax(S); S=concat(vector(#D, j, select(ispseudoprime, vector(#S, i, S[i]*n+D[j])))); ); m /* Max Alekseyev, Dec 06 2014 */

CROSSREFS

Cf. A023107 (where 1 is not considered to be prime).

Sequence in context: A033231 A139923 A097458 * A300165 A316351 A282633

Adjacent sequences:  A094332 A094333 A094334 * A094336 A094337 A094338

KEYWORD

base,nonn

AUTHOR

Martin Raab, Jun 04 2004

STATUS

approved

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Last modified March 20 05:47 EDT 2019. Contains 321344 sequences. (Running on oeis4.)