login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A138062 Prime number n, lesser of twin primes, both isolated from neighboring primes by more than +- 6. 1
419, 521, 809, 1049, 1151, 1721, 1931, 1949, 2027, 2111, 2309, 2591, 2729, 2999, 3119, 3359, 3371, 3389, 3557, 3581, 3821, 4229, 4241, 4271, 4337, 4421, 4481, 4547, 5021, 5879, 6089, 6131, 6299, 6449, 6689, 6761, 6779, 6791, 6947, 7307, 7331, 7349, 7559 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

419,421 = twin primes -- isolation +- 6 (or more)

419-2 = 417 (3*139) 421+2 = 423 (3*3*47)

419-4 = 415 (5*83) 421+4 = 425 (5*5*17)

419-6 = 413 (7*59) 421+6 = 427 (7*61)

MATHEMATICA

q=6; s=""; For[i=1, i<10^2*5, n=Prime[i]; m=n+2; If[PrimeQ[m], a=0; For[j=2, j<=q, If[PrimeQ[n-j]||PrimeQ[m+j], a=1; Break[]]; j=j+2]; If[a==0, s=s<>ToString[n]<>", "]]; i++ ]; Print[s]

tp6Q[b_]:=Module[{d=Differences[b]}, d[[2]]==2&&d[[1]]>6&&d[[3]]>6]; Transpose[ Select[Partition[Prime[Range[1000]], 4, 1], tp6Q]][[2]] (* Harvey P. Dale, Jan 10 2015 *)

CROSSREFS

Sequence in context: A224557 A292422 A328497 * A097233 A233551 A142281

Adjacent sequences:  A138059 A138060 A138061 * A138063 A138064 A138065

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 02 2008

EXTENSIONS

Definition corrected by and more terms from Harvey P. Dale, Jan 10 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 2 07:02 EST 2021. Contains 349437 sequences. (Running on oeis4.)