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A227447 Numbers k such that 3*5^(2*k)-3*5^k+1 is prime. 0
1, 2, 8, 25, 41, 66, 108, 318, 498, 546, 557, 846, 3780 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(14) > 10^4. - Daniel Suteu, Feb 13 2019

LINKS

Table of n, a(n) for n=1..13.

Eric L. F. Roettger, A Cubic Extension of the Lucas Functions, Ph. D. Dissertation, Dept. Math. and Statistics, Univ. Calgary, 2009 (see page 196).

MATHEMATICA

Select[Range[0, 3000], PrimeQ[3 5^(2 #) - 3 5^# + 1]&]

PROG

(PARI) is(n)=ispseudoprime(3*5^(2*n)-3*5^n+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A057917.

Sequence in context: A309088 A070944 A278836 * A077167 A062450 A198181

Adjacent sequences:  A227444 A227445 A227446 * A227448 A227449 A227450

KEYWORD

nonn,more

AUTHOR

Vincenzo Librandi, Jul 14 2013

EXTENSIONS

a(13) from Daniel Suteu, Feb 13 2019

STATUS

approved

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Last modified July 24 10:49 EDT 2021. Contains 346273 sequences. (Running on oeis4.)