A229855 384*n + 257.

257, 641, 1025, 1409, 1793, 2177, 2561, 2945, 3329, 3713, 4097, 4481, 4865, 5249, 5633, 6017, 6401, 6785, 7169, 7553, 7937, 8321, 8705, 9089, 9473, 9857, 10241, 10625, 11009, 11393, 11777, 12161, 12545, 12929, 13313, 13697, 14081, 14465, 14849, 15233, 15617

Offset

0,1

Comments

Every composite Fermat number has at least two divisors of the form 384*n + 257, n > 0.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 0..1000

Wikipedia, Fermat number

Index entries for linear recurrences with constant coefficients, signature (2,-1).

Formula

G.f.: (257 + 127*x)/(1 - x)^2.

a(n) = 128*A016789(n) + 1.

Maple

seq(384*n+257, n=0..40);

Mathematica

Table[384*n + 257, {n, 0, 40}]

Prog

(Magma) [384*n+257 : n in [0..40]]
(PARI) for(n=0, 40, print1(384*n+257, ", "));

Crossrefs

Cf. A000215, A094358, A229853, A229854, A229856.

Sequence in context: A250726 A142291 A208177 * A229856 A208178 A105131

Adjacent sequences: A229852 A229853 A229854 * A229856 A229857 A229858

Keyword

nonn,easy

Author

Arkadiusz Wesolowski, Oct 01 2013

Status

approved