A135165 a(n) = 7^n + 5^n - 3^n - 2^n.

0, 7, 61, 433, 2929, 19657, 132481, 899353, 6148609, 42286537, 292180801, 2025975673, 14084892289, 98108111017, 684321789121, 4778064706393, 33385475347969, 233393324169097, 1632227907493441, 11417967508915513, 79887630241419649, 559022690779036777, 3912205202988749761

Offset

0,2

Comments

Constants are the prime numbers in decreasing order.

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (17,-101,247,-210).

Formula

a(n) = 7^n + 5^n - 3^n - 2^n.

From Vincenzo Librandi, May 22 2014: (Start)

G.f.: 1/(1-7*x) + 1/(1-5*x) - 1/(1-3*x) - 1/(1-2*x).

a(n) = 17*a(n-1) - 101*a(n-2) + 247*a(n-3) - 210*a(n-4) for n>3. (End)

E.g.f.: exp(7*x) + exp(5*x) - exp(3*x) - exp(2*x). - G. C. Greubel, Sep 30 2016

Example

a(4) = 2929 because 7^4 = 2401, 5^4 = 625, 3^4 = 81, 2^4 = 16 and 2401+625-81-16 = 2929.

Mathematica

CoefficientList[Series[1/(1 - 7 x) + 1/(1 - 5 x) - 1/(1 - 3 x) - 1/(1 - 2 x), {x, 0, 40}], x] (* Vincenzo Librandi, May 22 2014 *)
LinearRecurrence[{17, -101, 247, -210}, {0, 7, 61, 433}, 30] (* Harvey P. Dale, Mar 20 2015 *)

Prog

(Magma)[7^n+5^n-3^n-2^n: n in [0..50]]; // Vincenzo Librandi, Dec 14 2010
(Magma) I:=[0, 7, 61, 433]; [n le 4 select I[n] else 17*Self(n-1)-101*Self(n-2)+247*Self(n-3)-210*Self(n-4): n in [1..30]]; // Vincenzo Librandi, May 22 2014
(PARI) a(n)=7^n+5^n-3^n-2^n \\ Charles R Greathouse IV, Sep 30 2016

Crossrefs

Cf. A000079, A000244, A000351, A000420, A001047, A074527, A007689, A135158, A135159, A135160.

Sequence in context: A275878 A129079 A249556 * A218805 A164943 A218228

Adjacent sequences: A135162 A135163 A135164 * A135166 A135167 A135168

Keyword

nonn,easy

Author

Omar E. Pol, Nov 21 2007

Status

approved