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A232725 Numbers n such that the concatenation 123456789n is prime. 1
1, 23, 29, 49, 133, 143, 167, 191, 199, 217, 257, 311, 403, 409, 419, 433, 437, 451, 457, 473, 563, 587, 601, 623, 629, 653, 671, 689, 721, 761, 769, 779, 803, 809, 851, 871, 881, 893, 913, 943, 947, 959, 1003, 1013, 1027, 1069, 1079, 1091, 1153, 1163, 1177 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..51.

EXAMPLE

721 is a member of this sequence because 123456789721 is prime.

PROG

(Python)

from sympy import isprime

{print(n, end=', ') for n in range(2000) if isprime(int("123456789"+str(n)))}

# Simplified by Derek Orr, Apr 10 2015

(PARI) for(n=1, 2000, if(isprime(eval(concat("123456789", Str(n)))), print1(n, ", "))) \\ Derek Orr, Apr 10 2015

(MAGMA) [n: n in [0..1500] | IsPrime(Seqint(Intseq(n) cat Intseq(123456789)))]; // Vincenzo Librandi, Apr 11 2015

CROSSREFS

Cf. A232726, A104914, A104915.

Sequence in context: A085713 A102904 A108249 * A045120 A174260 A097436

Adjacent sequences:  A232722 A232723 A232724 * A232726 A232727 A232728

KEYWORD

nonn,base

AUTHOR

Derek Orr, Nov 29 2013

EXTENSIONS

More terms from Derek Orr, Apr 10 2015

STATUS

approved

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Last modified April 25 13:31 EDT 2019. Contains 322461 sequences. (Running on oeis4.)