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
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
KEYWORD
easy,nonn
AUTHOR
Omar E. Pol, Nov 21 2007
EXTENSIONS
Edited by N. J. A. Sloane, Dec 14 2007
STATUS
approved