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A283559 Numbers k such that k![10]-2 is prime, where k![10] is the ten-fold multifactorial. 1
4, 5, 7, 9, 13, 15, 21, 25, 29, 31, 33, 41, 45, 49, 77, 195, 197, 199, 211, 309, 319, 345, 349, 395, 509, 533, 539, 597, 615, 705, 781, 803, 869, 969, 1313, 1317, 1331, 1335, 1337, 1429, 1597, 2121, 2133, 2513, 2547, 2733, 2885, 2931, 3701, 3709, 4681, 5911, 5933, 6125, 8191, 10637, 10679, 10845, 14901, 15629, 17165, 21691, 21867, 23119, 27033, 28601, 31245, 31957, 33289, 35773, 45011, 51079, 63241, 81369, 92615 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(76) > 50000.

The first 13 primes associated with this sequence: 2, 3, 5, 7, 37, 73, 229, 1873, 4957, 7159, 29599, 293599, 2953123.

LINKS

Table of n, a(n) for n=1..75.

C. Caldwell and H. Dubner (Eds): The top ten prime numbers: from the unpublished collections of R. Ondrejka (May 2001), Table 21 F, p. 75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

MATHEMATICA

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

Select[Range[2, 50000], PrimeQ[MultiFactorial[#, 10] - 2] &]

CROSSREFS

Cf. A076185, A085158, A094144, A204657.

Sequence in context: A263427 A052147 A139690 * A284190 A035266 A035264

Adjacent sequences:  A283556 A283557 A283558 * A283560 A283561 A283562

KEYWORD

nonn

AUTHOR

Robert Price, Mar 10 2017

EXTENSIONS

a(72)-a(75) from Robert Price, Apr 03 2017

STATUS

approved

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Last modified April 23 12:15 EDT 2021. Contains 343204 sequences. (Running on oeis4.)