

A220143


Numbers n that yield a new record for k such that n*k+1 and n*k1 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
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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



