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A344963 Numbers k such that (2*k+1)*k!+1 is prime. 1
0, 2, 3, 5, 11, 18, 68, 77, 124, 173, 205, 293, 1037, 1530, 1905, 2342, 3401, 4372, 4679, 5385 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(21) > 10^4.

LINKS

Table of n, a(n) for n=1..20.

MAPLE

select(k -> isprime((2*k+1)*k!+1), [$0 .. 300])[];

MATHEMATICA

Do[If[PrimeQ[(2*k + 1)*Factorial[k] + 1], Print[k]], {k, 0, 3000}]

PROG

(PARI) for(k=0, 3000, if(isprime((2*k+1)*k!+1), print1(k", ")))

(SageMath)

for k in range(3000):

    if is_prime((2*k+1)*factorial(k) + 1):

        print(k)

CROSSREFS

Cf. A002981, A344991.

Sequence in context: A057652 A025067 A024371 * A231479 A084758 A087582

Adjacent sequences:  A344960 A344961 A344962 * A344964 A344965 A344966

KEYWORD

nonn,hard,more

AUTHOR

Reza K Ghazi, Jun 07 2021

STATUS

approved

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Last modified August 7 20:35 EDT 2022. Contains 355994 sequences. (Running on oeis4.)