A232725 Numbers n such that the concatenation 123456789n is prime.

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

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: A102904 A108249 A338324 * 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