A037034 Least k such that 4*n*k-1 is a prime.

1, 1, 1, 2, 1, 1, 3, 1, 2, 2, 1, 1, 2, 3, 1, 2, 1, 1, 2, 1, 1, 3, 4, 2, 2, 1, 1, 2, 3, 2, 5, 1, 1, 2, 1, 3, 3, 1, 2, 3, 1, 1, 5, 7, 1, 2, 3, 1, 3, 1, 5, 5, 1, 2, 2, 1, 1, 2, 13, 1, 2, 3, 1, 5, 4, 1, 6, 1, 3, 3, 1, 3, 5, 3, 2, 2, 1, 1, 2, 4, 2, 3, 1, 7, 3, 3, 1, 5, 4, 1, 2, 1, 2, 2, 1, 1, 3, 4, 3, 5, 6, 3, 2, 4

Offset

1,4

Links

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

Example

a(5)=1 because 4*5*1-1=19 is a prime

Mathematica

lk[n_]:=Module[{c=4n, k=1}, While[!PrimeQ[c*k-1], k++]; k]; Array[lk, 110] (* Harvey P. Dale, Jun 05 2012 *)

Crossrefs

Cf. A016014.

Sequence in context: A228351 A124734 A337259 * A340056 A229897 A343796

Adjacent sequences: A037031 A037032 A037033 * A037035 A037036 A037037

Keyword

nonn

Author

Felice Russo

Extensions

More terms from Erich Friedman

Status

approved