OFFSET
1,2
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..10000
EXAMPLE
Let k = 5: The smallest number greater than 6 and coprime to 5*6 is 7. The smallest number greater than 7 and coprime to 5*6*7 is 11. Therefore k_2 = 7 and k_3 = 11. Since 5*6 + 7*11 and -5*6 + 7*11 are both primes, 5 is a term of the sequence.
MATHEMATICA
e = {}; For[n = 1, n < 250, n++, a = n; b = n + 1; c = n + 2; While[Not[GCD[c, n]*GCD[c, n + 1] == 1], c++ ]; d = c + 1; While[Not[GCD[d, a]*GCD[d, b]*GCD[d, c] == 1], d++ ]; If[PrimeQ[a*b + c*d], If[PrimeQ[ - a*b + c*d], AppendTo[e, n]]]]; e
CROSSREFS
KEYWORD
nonn,less
AUTHOR
J. M. Bergot, May 26 2007
EXTENSIONS
Edited, corrected and extended by Stefan Steinerberger, Nov 24 2007
STATUS
approved