OFFSET
1,1
COMMENTS
From the definition we see that the sequence is monotonic (but not strictly) increasing. The sequence is a generalized Cunningham chain. - Stefan Steinerberger, May 12 2007
EXAMPLE
a(2) = 13 because 13, 13*2-7=19 and 19*2-7=31 are primes.
MATHEMATICA
k = 5; For[n = 2, n <= 10, n++, While[Union[PrimeQ[NestList[2# - 7 &, Prime[k], n]], PrimeQ[NestList[2# - 7 &, Prime[k], n]]] != {True}, k++ ]; Print[Prime[k]]] (* Stefan Steinerberger, May 12 2007 *)
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Zak Seidov, May 07 2007
EXTENSIONS
Edited by Stefan Steinerberger, May 12 2007
Edited by Don Reble, Nov 07 2007
STATUS
approved