| 1, 1, 1, 2, 1, 3, 3, 2, 1, 15, 12, 6, 3, 5, 4, 2, 1, 6, 3, 11, 7, 11, 25, 20, 10, 5, 7, 15, 12, 6, 3, 35, 18, 9, 12, 6, 3, 15, 10, 5, 6, 3, 9, 9, 15, 35, 19, 27, 15, 14, 7, 14, 7, 20, 10, 5, 27, 29, 54, 27, 31, 36, 18, 9, 12, 6, 3, 9, 31, 23, 39, 39, 40, 20, 10, 5, 58, 29, 15, 36, 18, 9, 13
(list; graph; listen)
|
|
|
OFFSET
|
0,4
|
|
|
LINKS
|
T. D. Noe, Table of n, a(n) for n=0..1000
Index entries for sequences related to primes in arithmetic progressions
|
|
EXAMPLE
|
a(3)=2 because 1*2^3+1=9 is composite, 2*2^3+1=17 is prime.
a(99)=219 because 2^99k+1 is not prime for k=1,2,..,218. The first term which is not a composite number of this arithmetical progression is 2^99*219+1.
|
|
MATHEMATICA
|
a = {}; Do[k = 0; While[ ! PrimeQ[k 2^n + 1], k++ ]; AppendTo[a, k], {n, 0, 100}]; a (*Artur Jasinski*)
|
|
CROSSREFS
|
Analogous case is A034693. Special subscripts (n's for a(n)=1) are the exponents of known Fermat-primes: A000215. See also Fermat numbers A000051.
Cf. A007522, A127575, A127576, A127577, A127578, A127580, A127581, A087522, A127586.
Cf. A057778, A085427, A126717
Sequence in context: A088074 A071463 A047679 this_sequence A046819 A159945 A089216
Adjacent sequences: A035047 A035048 A035049 this_sequence A035051 A035052 A035053
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu)
|
|
