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A135168 a(n) = 7^n + 5^n + 3^n + 2^n. 1
4, 17, 87, 503, 3123, 20207, 134067, 903983, 6162243, 42326927, 292300947, 2026334063, 14085963363, 98111316047, 684331387827, 4778093469743, 33385561572483, 233393582711567, 1632228682858707, 11417969834487023, 79887637217085603, 559022711703937487 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Constants  (7,5,3,2) are the prime numbers in decreasing order.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

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

FORMULA

From G. C. Greubel, Sep 30 2016: (Start)

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

G.f.: (4 - 51*x + 202*x^2 - 247*x^3)/((1 -2*x)*(1 -3*x)*(1 -5*x)*(1 -7*x)).

E.g.f.: exp(7*x) + exp(5*x) + exp(3*x) + exp(2*x). (End)

EXAMPLE

a(4) = 3123 = 7^4 + 5^4 + 3^4 + 2^4 = 2401 + 625 + 81 + 16.

MAPLE

A135168:=n->7^n+5^n+3^n+2^n; seq(A135168(k), k=0..100); # Wesley Ivan Hurt, Nov 05 2013

MATHEMATICA

Table[7^n+5^n+3^n+2^n, {n, 0, 100}] (* Wesley Ivan Hurt, Nov 05 2013 *)

LinearRecurrence[{17, -101, 247, -210}, {4, 17, 87, 503}, 25] (* G. C. Greubel, Sep 30 2016 *)

PROG

(MAGMA) [7^n+5^n+3^n+2^n: n in [0..25]]; // Vincenzo Librandi, Jun 11 2011

(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, A001551.

Sequence in context: A056542 A110508 A114190 * A058279 A143405 A303793

Adjacent sequences:  A135165 A135166 A135167 * A135169 A135170 A135171

KEYWORD

easy,nonn

AUTHOR

Omar E. Pol, Nov 21 2007

EXTENSIONS

Edited by N. J. A. Sloane, Dec 14 2007

STATUS

approved

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Last modified March 20 15:43 EDT 2019. Contains 321345 sequences. (Running on oeis4.)