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A272143 For a given n, and any m less than n-1, the total number of primes of the form 2^n-2^m-1. 1
0, 1, 1, 2, 2, 3, 0, 4, 4, 3, 1, 5, 1, 4, 0, 3, 2, 8, 1, 11, 4, 5, 0, 7, 1, 2, 0, 1, 5, 4, 0, 7, 5, 1, 1, 9, 0, 6, 0, 7, 1, 6, 0, 4, 7, 2, 1, 10, 3, 3, 1, 2, 1, 6, 0, 4, 3, 0, 1, 8, 3, 3, 0, 3, 1, 8, 1, 2, 2, 3, 0, 9, 1, 5, 2, 5, 8, 3, 0, 10 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

For the first 12000 terms the average is ~3.8 with a maximum of 25 at a(11520).

Essentially the same as A095058. - R. J. Mathar, Apr 24 2016

LINKS

Hans Havermann, Table of n, a(n) for n = 1..12000

Hans Havermann, Table of n, {m1, m2, ...} for primes of the form 2^n-2^m-1, m<n-1.

EXAMPLE

For n=1, m<0, so there are no solutions. For n=2 there is one solution: m=0, yielding prime 2. For n=3, one solution: m=1, yielding prime 5. For n=4 there are two solutions: m=2 and m=1, yielding primes 11 and 13 respectively. The primes so formed are terms of A095078.

MATHEMATICA

Table[Length[Select[Table[2^n - 2^m - 1, {m, 0, n - 2}], PrimeQ[#] & ]], {n, 1, 100}] (* Robert Price, Apr 21 2016 *)

CROSSREFS

Cf. A095078.

Sequence in context: A263254 A257989 A095201 * A095058 A137345 A060755

Adjacent sequences:  A272140 A272141 A272142 * A272144 A272145 A272146

KEYWORD

nonn

AUTHOR

Hans Havermann, Apr 21 2016

STATUS

approved

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Last modified September 29 09:25 EDT 2020. Contains 337428 sequences. (Running on oeis4.)