A230527 -id:A230527 - cp's OEIS frontend

A230537 Numbers n such that 3^7*2^n - 1 is prime.

1, 2, 6, 13, 22, 29, 30, 33, 36, 50, 61, 118, 180, 226, 405, 433, 522, 789, 929, 960, 1026, 1030, 1118, 1266, 1521, 1718, 2536, 3029, 3366, 4253, 9157, 10165, 23641, 29877, 30648, 47265, 56097, 90501, 101981, 103021, 108370, 117909, 157237, 169156, 174168

Offset: 1

Lei Zhou, Oct 22 2013

Riesel Primes with k = 3^7 = 2187.

Checked up to n = 1000000.

			2187*2^1-1=4373 is a prime number.

Lei Zhou, Table of n, a(n) for n = 1..52
K. Bonath, Riesel Prime Database
C. K. Caldwell, a(51) = 2187*2^449776-1
C. K. Caldwell, a(52) = 2187*2^916686-1
C. K. Caldwell, a(53) = 2187*2^992632-1

Cf. A002235, A002236, A050539, A050566, A050880, A230527.

b=3^7;i=0; Table[While[i++; cp=b*2^i-1; !PrimeQ[cp]]; i, {j, 1, 30}]

is(n)=ispseudoprime(3^7*2^n-1) \\ Charles R Greathouse IV, May 22 2017

Lei Zhou, Nov 08 2013, added a Mathematica program for small elements.

A212311 Numbers n such that 3^8*2^n - 1 is prime.

Original entry on oeis.org

1, 15, 33, 43, 61, 121, 295, 315, 367, 681, 771, 789, 1485, 4915, 5305, 33649, 81343, 85005, 116307, 154869, 230731, 279591, 287847, 329515, 545353, 1053481

Offset: 1

Lei Zhou, Oct 24 2013

Riesel Primes with k = 3^8 = 6561.

Checked up to n = 1053627.

			6561*2^1-1=13121 is a prime number.

K. Bonath,Riesel Prime Database
C. K. Caldwell, 6561*2^1053481-1

Cf. A002235, A002236, A050539, A050566, A050880, A230527, A230537.

b=2^8;i=0; Table[While[i++; cp=b*2^i-1; !PrimeQ[cp]]; i, {j, 1, 13}]

is(n)=ispseudoprime(3^8*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

Lei Zhou, Nov 08 2013, added a Mathematica program for small elements.

A231374 Numbers n such that 3^9*2^n - 1 is prime.

Original entry on oeis.org

4, 7, 19, 22, 32, 46, 50, 62, 83, 103, 124, 142, 190, 230, 256, 260, 422, 596, 1084, 2270, 2770, 5366, 5434, 5762, 6826, 9239, 15211, 22556, 58790, 81319, 172510, 225350, 236326, 258592, 445364, 975020

Offset: 1

Lei Zhou, Nov 08 2013

Riesel Primes with k = 3^9 = 19683.

Checked up to n = 1000000.

			19683*2^4-1=314927 is a prime number.

Cf. A002235, A002236, A050539, A050566, A050880, A230527, A230537, A212311.

i=0;Table[While[i++;cp=19683*2^i-1;!PrimeQ[cp]];i,{j,1,20}]

is(n)=ispseudoprime(3^9*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

cp's OEIS Frontend

A230537 Numbers n such that 3^7*2^n - 1 is prime.

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A212311 Numbers n such that 3^8*2^n - 1 is prime.

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A231374 Numbers n such that 3^9*2^n - 1 is prime.

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Author

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Examples

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Programs

Mathematica

PARI