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A177103 Numbers n >= 0 such that 2*3^n - 1 is not prime. 1
0, 4, 5, 6, 9, 10, 11, 13, 14, 15, 16, 17, 18, 19, 21, 22, 24, 25, 26, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

Select[Range[0, 100], !PrimeQ[2*3^# - 1] &] (* Vincenzo Librandi, Oct 15 2012 *)

PROG

(MAGMA) [ n: n in [0..100] | not IsPrime(2*3^n-1) ];

CROSSREFS

Cf. A003307 (Numbers n such that 2*3^n-1 is prime).

Sequence in context: A139546 A029776 A064931 * A114454 A008854 A062726

Adjacent sequences:  A177100 A177101 A177102 * A177104 A177105 A177106

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi

STATUS

approved

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Last modified May 25 01:25 EDT 2019. Contains 323534 sequences. (Running on oeis4.)