A110705 Numbers n such that "n 42's followed by 43" is prime.

0, 1, 2, 3, 4, 7, 17, 24, 59, 199, 743, 2558, 4896, 5539, 6192, 10977, 27679

Offset: 1

Author

Ray Chandler, Aug 04 2005

Keywords

• nonn
• base
• more

Comments

Equivalently, a(n) generates primes of the form (100^(1+a(n)) - 1) * 42/99 + 1. - Mohsen Hozan, Jan 23 2015

Crossrefs

Cf. A110704, A254002.

Programs

Mathematica

t = 1; Do[ t = t*100 - 57; If[PrimeQ[t], Print[n]], {n, 0, 3000}]
robinsonQ[n_] := PrimeQ[(100^(1 + n) - 1) * 42/99 + 1]; Select[Range[200], robinsonQ] (* Robert G. Wilson v, Jan 23 2015 *)

PARI

t=1; for(n=0,10^6,t=100*t-57;if(ispseudoprime(t),print1(n,", "))); \\ Joerg Arndt, Nov 21 2014

PFGW

ABC2 1+(100^(1+$a)-1)*42/99
a: from 0 to 28000 \\ Charles R Greathouse IV, Mohsen Hozan, Jan 23 2015

Extensions

a(13)-a(17) from Mohsen Hozan, Feb 10 2015