A089635 Smallest member of a pair of consecutive twin prime pairs that have three primes between them.

107, 239, 311, 569, 1229, 1427, 1997, 2687, 4049, 4127, 4157, 4481, 5231, 6089, 7559, 9629, 10457, 13829, 13901, 14249, 16187, 16649, 17207, 17597, 17957, 18059, 19841, 20507, 21317, 21491, 21557, 22481, 27689, 28109, 28277, 28349, 31769, 32141

Offset

3,1

Links

Harvey P. Dale, Table of n, a(n) for n = 3..1000

Mathematica

Transpose[Select[Partition[Prime[Range[6, 4000]], 7, 1], #[[2]]-#[[1]]== #[[7]]- #[[6]] ==2&&#[[4]]-#[[3]]!=2&&#[[5]]-#[[4]]!=2&]][[1]](* Harvey P. Dale, Oct 07 2014 *)

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", ")) ) } savetwins(n) = \ build a twin prime table of lower bounds { twin = vector(n); c=1; forprime(x=3, n*10, if(isprime(x+2), twin[c]=x; c++; ) )

Crossrefs

Cf. A105413.

Sequence in context: A141996 A142844 A142914 * A248402 A201220 A088563

Adjacent sequences: A089632 A089633 A089634 * A089636 A089637 A089638

Keyword

easy,nonn

Author

Cino Hilliard, Jan 01 2004

Extensions

Cross-reference added by Harvey P. Dale, Oct 08 2014

Status

approved