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A231652
Lesser twin prime p such that p^2-p-2 is the average of a larger twin prime pair.
1
5, 11, 17, 29, 71, 197, 269, 1277, 1289, 1607, 2027, 2111, 2267, 2687, 3467, 4649, 6359, 6761, 6827, 7877, 9461, 10529, 12917, 13337, 13691, 13829, 13931, 17291, 17579, 20441, 20771, 26249, 29021, 29129, 34589, 34649, 38237, 39239, 44027, 47417, 49547, 51347
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
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
Subsequence of A001359.
Sequence in context: A268518 A268521 A230138 * A321792 A068072 A136292
KEYWORD
nonn
AUTHOR
Michael G. Kaarhus, Nov 12 2013
STATUS
approved