A061410 Numbers k such that m*2^k+1 is not prime for all coefficients m in the range 0<=m<=k.

9, 10, 22, 31, 86, 99, 100, 101, 113, 114, 115, 130, 135, 136, 149, 154, 169, 217, 218, 223, 224, 283, 301, 309, 358, 383, 384, 422, 423, 424, 425, 426, 449, 457, 473, 495, 505, 506, 541, 542, 548, 549, 564, 571, 572, 573, 628, 668, 670, 681, 682, 683, 713

Offset: 1

Author

Patrick De Geest, May 15 2001

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..285

Crossrefs

Cf. A061411, A061412, A061413, A061414, A061415.

Programs

Maple

filter:= n -> andmap(not isprime, [seq(m*2^n+1,m=1..n)]):
select(filter, [$1..1000]); # Robert Israel, Dec 10 2017

Mathematica

okQ[n_] := AllTrue[2^n Range[n] + 1, CompositeQ];
Select[Range[1000], okQ] (* Jean-François Alcover, Mar 25 2019 *)

PARI

isok(n) = {for (m=0, n, if (isprime(m*2^n+1), return (0));); return (1);} \\ Michel Marcus, Dec 11 2017