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

1,3

Comments

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

Links

Table of n, a(n) for n=1..17.

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 *)

Prog

(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

Crossrefs

Cf. A110704, A254002.

Sequence in context: A068194 A179985 A338928 * A139439 A352902 A119330

Adjacent sequences: A110702 A110703 A110704 * A110706 A110707 A110708

Keyword

nonn,base,more

Author

Ray Chandler, Aug 04 2005

Extensions

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

Status

approved