OFFSET
0,1
COMMENTS
Constants are the prime numbers in decreasing order.
LINKS
G. C. Greubel, 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.
a(0)=2, a(1)=11, a(2)=69, a(3)=449, a(n) = 17*a(n-1) - 101*a(n-2) + 247*a(n-3) - 210*a(n-4). - Harvey P. Dale, Feb 01 2013
From G. C. Greubel, Sep 30 2016: (Start)
G.f.: (2 - 23*x + 84*x^2 - 107*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) = 2961 because 7^4 = 2401, 5^4 = 625, 3^4 = 81, 2^4 = 16 and we can write 2401 + 625 - 81 + 16 = 2961.
MATHEMATICA
Table[7^n+5^n-3^n+2^n, {n, 0, 30}] (* or *) LinearRecurrence[ {17, -101, 247, -210}, {2, 11, 69, 449}, 30] (* Harvey P. Dale, Feb 01 2013 *)
PROG
(Magma)[7^n+5^n-3^n+2^n: n in [0..50]] // Vincenzo Librandi, Dec 14 2010
(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
More terms from Vincenzo Librandi, Dec 14 2010
STATUS
approved