A220143 - OEIS

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A220143

Numbers n that yield a new record for k such that n*k+1 and n*k-1 are twin primes.

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

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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.

LINKS

Table of n, a(n) for n=1..38.

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

Cf. A071558, A220144.

Sequence in context: A161537 A248634 A189724 * A217470 A308010 A180486

Adjacent sequences: A220140 A220141 A220142 * A220144 A220145 A220146

KEYWORD

nonn

AUTHOR

T. D. Noe, Jan 08 2013

EXTENSIONS

More terms from Amiram Eldar, Dec 30 2019

STATUS

approved