OFFSET
1,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,-2).
FORMULA
a(n) = 2*a(n-1) + 17, a(1) = 15.
a(n) = 16*2^n - 17.
From Colin Barker, Jan 25 2012: (Start)
a(n) = 3*a(n-1) - 2*a(n-2), a(1)=15, a(2)=47.
G.f.: x*(15+2*x)/(1-3*x+2*x^2). (End)
E.g.f.: 16*exp(2*x) - 17*exp(x) + 1. - G. C. Greubel, Apr 26 2016
MATHEMATICA
(*1*) fp[n_]:=FixedPoint[Mod[(#+2^#), 17+# ]&, n] NestList[fp[2#+17]&, 15, 10]
(*2*)NestList[2*#+17&, 15, 40]
LinearRecurrence[{3, -2}, {15, 47}, 10] (* G. C. Greubel, Apr 26 2016 *)
PROG
(PARI) a(n)=([0, 1; -2, 3]^n*[-1; 15])[1, 1] \\ Charles R Greathouse IV, Apr 29 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Zak Seidov, Oct 07 2009
STATUS
approved