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A329112

Numbers k such that k![4] - 8 is prime, where k![4] = A007662(k) = quadruple factorial.

7, 9, 11, 13, 15, 19, 21, 23, 29, 35, 37, 55, 57, 77, 85, 139, 243, 251, 433, 667, 671, 895, 2127, 2263, 2293, 2645, 2733, 2845, 3675, 4381, 6453, 6825, 36557, 78531

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OFFSET

1,1

COMMENTS

a(35) > 10^5.

The first 6 primes associated with this sequence are: 13, 37, 223, 577, 3457, 65827.

LINKS

Table of n, a(n) for n=1..34.

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C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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

MATHEMATICA

MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];

Select[Range[1000], (x = MultiFactorial[#, 4] - 8; x > 0 && PrimeQ[x]) &]

CROSSREFS

Cf. A007662, A283553.

Sequence in context: A059808 A020742 A193071 * A347886 A023389 A248963

Adjacent sequences: A329109 A329110 A329111 * A329113 A329114 A329115

KEYWORD

nonn

AUTHOR

Robert Price, Nov 06 2019

STATUS

approved