

A035789


Start of a string of exactly 1 consecutive (but disjoint) pair of twin primes.


16



29, 41, 59, 71, 227, 239, 269, 281, 311, 347, 461, 521, 569, 599, 617, 641, 659, 857, 881, 1091, 1151, 1229, 1277, 1289, 1301, 1319, 1427, 1451, 1607, 1619, 1667, 1697, 1721, 1787, 1997, 2027, 2141, 2237, 2267, 2309, 2339, 2381, 2549, 2591, 2657, 2687
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OFFSET

1,1


COMMENTS

Lesser of lonely twin primes.
Old Name was: Let P1,P2,..,P6 be any 6 consecutive primes. The sequence consists of those values of P3 for which P2P1>2, P4P3=2 and P6P5>2.


LINKS

Sebastian Petzelberger, Table of n, a(n) for n = 1..10000
Hugo Pfoertner, FORTRAN program: Consecutive pairs of twin primes.
Randall Rathbun, A study of ntwin_prime clusters among prime numbers, Posting to Number Theory List, Nov 19 1998.


EXAMPLE

The first lonely twin primes (A069453) are 29,31 (23 and 37 are nontwin), 41,43 (37 and 47 are nontwin), 59,61 (53 and 67 are nontwin). Of these, the lesser twins are 29,41,59, so this is how the sequence begins.
23, 27, 29, 31, 37, 41: 2723>2, 3129=2, 4137>2; so 29 is in the sequence.
From Hartmut F. W. Hoft, Apr 05 2016: (Start)
The example should read: 19, 23, 29, 31, 37, 41: 2319>2, 3129=2, 4137>2; so 29 is in the sequence.
a(n)=A069453(2n1), n>=1.
(End)


MATHEMATICA

PrimeNext[n_]:=Module[{k}, k=n+1; While[ !PrimeQ[k], k++ ]; k]; PrimePrev[n_]:=Module[{k}, k=n1; While[ !PrimeQ[k], k ]; k]; lst={}; Do[p=Prime[n]; If[ !PrimeQ[p2]&&!PrimeQ[p+4]&&PrimeQ[p+2]&&!PrimeQ[PrimePrev[p]2]&&!PrimeQ[PrimeNext[p+2]+2], AppendTo[lst, p]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jul 22 2009 *)
(* starting at n=3 would eliminate the first two primality tests, Hartmut F. W. Hoft, Apr 09 2016 *)


CROSSREFS

Cf. A035790, A035791, A035792, A035793, A035794, A035795, A087641.
Cf. A069453, A069455.
Sequence in context: A068480 A161616 A069454 * A343478 A343479 A080899
Adjacent sequences: A035786 A035787 A035788 * A035790 A035791 A035792


KEYWORD

nonn,easy


AUTHOR

Randall Rathbun, Nov 30 1998


EXTENSIONS

Edited by Hugo Pfoertner, Oct 15 2003


STATUS

approved



