OFFSET
1,1
COMMENTS
There are 265364 members of this sequence up to 10^10, so about 1% of twin primes with fewer than 10 digits are in this sequence. - Charles R Greathouse IV, Nov 12 2013
LINKS
Michael G. Kaarhus, Table of n, a(n) for n = 1..10000
M. G. Kaarhus, newprime.pdf
EXAMPLE
17 is in this sequence because 17 is a lesser twin prime and 17^2 - 17 - 2 is the average of 269 and 271 which is a pair of twin primes.
PROG
(Maxima) y:0$ p:0$ c:0$ f(p):= p^2-p-2$ for p:5 thru 100000 step 6 do (if(primep(p) and primep(p+2)) then (y:f(p), if(primep(y-1) and primep(y+1)) then (c:c+1, print(c, ", ", p, ", ", y))))
(PARI) is(n)=isprime(n^2-n-3) && isprime(n^2-n-1) && isprime(n+2) && isprime(n) && n>3 \\ Charles R Greathouse IV, Nov 12 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael G. Kaarhus, Nov 12 2013
STATUS
approved