A242487 -id:A242487 - cp's OEIS frontend

A300947 Primes of form (2*k)! + k! + 1.

3, 727, 20922789928321, 403291461126605641811020801, 523022617466601111760007224221719391608832001

Offset: 1

Seiichi Manyama, Mar 22 2018

nonn

The next term is too large to include.

select(isprime,[seq(factorial(2*k)+factorial(k)+1,k=0..600)]); # Muniru A Asiru, May 27 2018

lista(nn) = {for(k=0, nn, if(ispseudoprime(p=(2*k)!+k!+1), print1(p, ", ")));} \\ Altug Alkan, Mar 22 2018

a(n) = (2*A242487(n))! + A242487(n)! + 1.

A303737 Numbers k such that (2*k)! + k! - 1 is prime.

Original entry on oeis.org

1, 4, 18, 49, 60, 82, 321, 6328

Offset: 1

Muniru A Asiru, May 27 2018

a(9) > 10000. - Giovanni Resta, Jun 07 2018

			1 is a term because (2*1)! + 1! - 1 = 2 which is a prime.
4 is a term because (2*4)! + 4! - 1 = 40343 which is a prime.

Cf. A242487, A300947, A303738 (corresponding primes).

select(k->isprime(factorial(2*k)+factorial(k)-1),[$1..1000]);

isok(k) = isprime((2*k)! + k! - 1); \\ Michel Marcus, May 28 2018

a(8) from Giovanni Resta, Jun 07 2018

A303738 Primes of form (2*k)! + k! - 1.

Original entry on oeis.org

2, 40343, 371993326789901217467999454553208905727999

Offset: 1

Muniru A Asiru, May 27 2018

nonn

a(4) has 154 digits and is too large to be included.

Cf. A242487, A300947, A303737.

f:=factorial: select(isprime,[seq(f(2*k)+f(k)-1,k=1..600)]);

a(n) = (2*A303737(n))! + A303737(n)! - 1.

cp's OEIS Frontend

A300947 Primes of form (2*k)! + k! + 1.

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A303737 Numbers k such that (2*k)! + k! - 1 is prime.

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A303738 Primes of form (2*k)! + k! - 1.

Views

Author

Keywords

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Programs

Maple

Formula