The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A261316 Numbers n such that n!!! - 3^n is prime. 1
 68, 88, 91, 118, 131, 151, 157, 194, 203, 424, 602, 772, 832, 884, 947, 1309, 1463, 2246, 3304, 4043, 5725, 6683, 9344, 10969, 11026, 11735, 13664, 14857, 18529, 21676, 28217, 28793, 29605, 33206, 41182, 43777, 49936 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS n!!! is the triple factorial sometimes written n!3. If taking absolute values: 1,2,5,8,13,26,29,31,41,43,44,46,56,59 would also be in this sequence. a(38) > 50000. LINKS EXAMPLE 68 is in the sequence because 68!!!-3^68=350834017732995704466119535768239 is prime. MATHEMATICA MultiFactorial[n_, k_] := If[n < 1, 1, If[n < k + 1, n, n*MultiFactorial[n - k, k]]]; Select[Range[0, 100], MultiFactorial[#, 3] - 3^# > 0 && PrimeQ[MultiFactorial[#, 3] - 3^#] &] CROSSREFS Cf. A007661, A124248, A124249. Sequence in context: A039433 A043256 A044036 * A045268 A217776 A039540 Adjacent sequences:  A261313 A261314 A261315 * A261317 A261318 A261319 KEYWORD nonn AUTHOR Robert Price, Aug 14 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 8 02:27 EDT 2020. Contains 333312 sequences. (Running on oeis4.)