VOOZH about

URL: https://oeis.org/A220143

⇱ A220143 - OEIS

login
A220143
Numbers n that yield a new record for k such that n*k+1 and n*k-1 are twin primes.
2
1, 5, 8, 11, 13, 31, 37, 53, 61, 433, 1957, 2047, 2603, 4079, 9967, 10789, 76943, 81439, 121763, 206867, 233969, 276349, 495931, 626939, 2055943, 3144937, 3585509, 3810949, 6274823, 8407129, 9299471, 19279903, 35531621, 36426301, 38235389, 71701529, 76384717, 98566373
OFFSET
1,2
COMMENTS
These are numbers at which A071558 reaches a new record. The corresponding values of k are in A220144. Note that these numbers are not all primes.
MATHEMATICA
t = {{1, 4}}; Do[k = 1; While[! (PrimeQ[k*n - 1] && PrimeQ[k*n + 1]), k++]; If[k > t[[-1, 2]], AppendTo[t, {n, k}]], {n, 2, 100000}]; Transpose[t][[1]]
CROSSREFS
Sequence in context: A161537 A248634 A189724 * A217470 A308010 A180486
KEYWORD
nonn
AUTHOR
T. D. Noe, Jan 08 2013
EXTENSIONS
More terms from Amiram Eldar, Dec 30 2019
STATUS
approved