A177103 - OEIS

A177103

Numbers n >= 0 such that 2*3^n - 1 is not prime.

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

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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: A308886 A029776 A064931 * A114454 A008854 A062726

Adjacent sequences: A177100 A177101 A177102 * A177104 A177105 A177106

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi

STATUS

approved