A328454 Numbers k such that k![4] - 4 is prime, where k![4] = A007662(k) = quadruple factorial.

7, 9, 11, 15, 17, 19, 39, 45, 57, 59, 63, 69, 81, 85, 127, 141, 149, 153, 163, 165, 201, 235, 259, 377, 457, 649, 815, 897, 1057, 1433, 1453, 1519, 1759, 3047, 3561, 4151, 7025, 11917, 11971, 15295, 18919, 19449, 20765, 70385, 71293

Offset: 1

Author

Robert Price, Nov 06 2019

Keywords

• nonn

Comments

a(46) > 10^5.

The first 6 primes associated with this sequence are: 17, 41, 227, 3461, 9941, 65831.

Links

• C. K. Caldwell, The Prime Glossary, multifactorial prime
• C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75
• Ken Davis, Status of Search for Multifactorial Primes.
• Joe McLean, Interesting Sources of Probable Primes

Crossrefs

Cf. A007662, A283553.

Programs

Mathematica

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
Select[Range[1000], (x = MultiFactorial[#, 4] - 4; x > 0 && PrimeQ[x]) &]