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A110705
Numbers n such that "n 42's followed by 43" is prime.
2
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
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
Sequence in context: A375283 A179985 A338928 * A139439 A376735 A352902
KEYWORD
nonn,base,more
AUTHOR
Ray Chandler, Aug 04 2005
EXTENSIONS
a(13)-a(17) from Mohsen Hozan, Feb 10 2015
STATUS
approved