OFFSET
1,4
COMMENTS
Conjecture: a(n)>0; equivalently, for every n, the arithmetic progression {6*k*n-1} contains infinitely many lessers of twin primes (A001359).
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
Table[k = 0; While[! (PrimeQ[6*k*n - 1] && PrimeQ[6*k*n + 1]), k++]; k, {n, 100}] (* T. D. Noe, May 02 2012 *)
PROG
(PARI) a(n)=my(k); n*=6; until(isprime(n*k++-1)&&isprime(n*k+1), ); k \\ Charles R Greathouse IV, May 01 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, May 01 2012
STATUS
approved