A248351 Numbers k such that 10^k + 987654321 is prime.

6, 11, 15, 27, 42, 113, 135, 186, 207, 503, 2999, 3005, 3487, 5718, 7265, 7629, 11987, 16063, 27379, 64770, 73579, 96504, 116557

Offset: 1

Author

Derek Orr, Oct 05 2014

Keywords

• nonn
• hard
• more

Comments

Note that 987654321 is the largest pandigital number in base-10, omitting 0.

Crossrefs

Cf. A248349, A248350, A248352, A050289.

Programs

Magma

[n: n in [1..500] | IsPrime(10^n+987654321)]; // Vincenzo Librandi, Oct 12 2014

Mathematica

Select[Range[1000], PrimeQ[10^# + 987654321] &] (* Vincenzo Librandi, Oct 12 2014 *)

PARI

for(n=1,10^4,if(ispseudoprime(10^n+987654321),print1(n,", ")))

Extensions

a(9) corrected and a(19)-a(23) added by Robert Price, Dec 05 2019