A089629 Smallest member of a pair of consecutive twin prime pairs that have one prime between them.

17, 29, 59, 227, 269, 617, 1031, 1277, 1289, 1301, 1607, 1667, 1697, 2087, 2129, 2309, 2711, 2789, 3257, 3527, 3539, 3557, 3917, 4019, 4241, 4517, 4637, 4787, 5477, 5501, 5639, 6551, 7307, 8819, 8837, 8999, 9011, 10037, 10067, 10271, 10499, 12041, 13679

Offset

1,1

Comments

Run the PARI script savetwins(100000) or so to build the twinprime array of lower bounds before you run the main script.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

Twin prime pairs 17,19 and 29,31 have only the prime 23 between them.

Prog

(PARI) pbetweentw(n, p) = \p is the number of primes between { forstep(x1=1, n, 1, c=0; t1 = twin[x1]; t2 = twin[x1+1]; for(y=t1+4, t2-1, if(isprime(y), c++) ); if(c==p, print1(t1", ")) ) } \ build a twin prime table of lower bounds savetwins(n) = { twin = vector(n); c=1; forprime(x=3, n*10, if(isprime(x+2), twin[c]=x; c++; ) ) }

Crossrefs

Sequence in context: A342820 A190556 A241485 * A007349 A154616 A196938

Adjacent sequences: A089626 A089627 A089628 * A089630 A089631 A089632

Keyword

easy,nonn

Author

Cino Hilliard, Jan 01 2004

Extensions

Offset corrected by Amiram Eldar, Dec 28 2019

Status

approved