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A135972 Nonprime numbers of the form 2^n-1. 2
0, 1, 15, 63, 255, 511, 1023, 2047, 4095, 16383, 32767, 65535, 262143, 1048575, 2097151, 4194303, 8388607, 16777215, 33554431, 67108863, 134217727, 268435455, 536870911, 1073741823, 4294967295, 8589934591, 17179869183, 34359738367 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..28.

MATHEMATICA

k = {}; Do[If[ ! PrimeQ[2^n - 1], AppendTo[k, 2^n - 1]], {n, 1, 100}]; k

PROG

(PARI) lista(nn) = for (n=0, nn, if (! isprime(np = 2^n-1), print1(np, ", "))); \\ Michel Marcus, Nov 04 2013

CROSSREFS

Subsequence of A000225.

Sequence in context: A157968 A141759 A104473 * A138104 A152099 A119496

Adjacent sequences:  A135969 A135970 A135971 * A135973 A135974 A135975

KEYWORD

nonn

AUTHOR

Artur Jasinski, Dec 09 2007

STATUS

approved

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Last modified August 28 15:16 EDT 2015. Contains 261125 sequences.