A138582 Numbers k such that 2^(2*k-19) - 19 is prime.

12, 13, 15, 17, 19, 20, 25, 29, 43, 44, 52, 88, 95, 105, 137, 155, 199, 1844, 2285, 4775, 6569, 7115, 10333

Offset

1,1

Comments

a(24) > 50000. - Michael S. Branicky, May 20 2026

Links

Table of n, a(n) for n=1..23.

Example

2^(2*15-19)-19 = 2029, 2^(2*17-19)-19 =32749, ...

Mathematica

q=19; For[i=q, i<=q, a={}; Do[x=2^(2*n-i)-i; If[PrimeQ[x], AppendTo[a, n]], {n, 10^2}]; Print["2^(2*n-", i, ")-", i, " ", a]; i=i+2]

Prog

(PARI) is(n)=isprime(2^(2*n-19)-19) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A138577, A138578, A138579, A138580, A138581.

Cf. A138598, A138599, A138600, A138601, A138602, A138603.

Sequence in context: A354746 A136200 A096514 * A074163 A076979 A365589

Adjacent sequences: A138579 A138580 A138581 * A138583 A138584 A138585

Keyword

nonn,more

Author

Vladimir Joseph Stephan Orlovsky, May 13 2008

Extensions

Terms 10 and 11 removed and a(18)-a(23) from Michael S. Branicky, May 20 2026

Status

approved