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 A243078 Numbers n such that n!3 - 3^2 is prime, where n!3 = n!!! is a triple factorial number (A007661). 13
 7, 8, 10, 13, 16, 17, 20, 23, 28, 29, 32, 43, 46, 47, 53, 56, 59, 61, 76, 95, 107, 139, 148, 218, 349, 764, 1009, 1130, 1183, 1429, 1516, 2072, 2471, 4937, 10204, 13993, 16249, 18166, 25733, 29033, 40090 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(42) > 50000. n=2 and n=4 produce values (-7 and -5) whose absolute value is a prime. Terms > 2000 correspond to probable primes. LINKS Henri & Renaud Lifchitz, PRP Records. Search for n!3-9. OpenPFGW Project, Primality Tester EXAMPLE 17!3 - 3^2 = 17*14*11*8*5*2 - 9 = 209431 is prime, so 17 is in the sequence. - Jens Kruse Andersen, Aug 20 2014 MATHEMATICA MultiFactorial[n_, k_]:=If[n<1, 1, If[n

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Last modified June 15 17:43 EDT 2019. Contains 324142 sequences. (Running on oeis4.)