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A006552 Numbers k such that k*3^k + 1 is prime.
(Formerly M1848)
8
2, 8, 32, 54, 114, 414, 1400, 1850, 2848, 4874, 7268, 19290, 337590, 1183414 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
H. Dubner, Generalized Cullen numbers, J. Rec. Math., 21 (No. 3, 1989), 190-191. (Annotated scanned copy)
MATHEMATICA
Select[Range[10000], PrimeQ[# 3^# + 1] &] (* Vincenzo Librandi, Dec 02 2015 *)
PROG
(Magma) [n: n in [0..420] | IsPrime(n*3^n+1)]; // Vincenzo Librandi, Dec 02 2015
(PARI) is(n)=ispseudoprime(n*3^n+1) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Sequence in context: A026369 A269818 A331823 * A134753 A212892 A302936
KEYWORD
nonn,hard
AUTHOR
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(14) from Loeh link by Ray Chandler, Apr 10 2016
STATUS
approved

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Last modified July 22 16:55 EDT 2024. Contains 374540 sequences. (Running on oeis4.)