OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,1,-1).
FORMULA
a(n) = (10*n + 7 + 5*(-1)^n)/4. - Jon E. Schoenfield, Jun 24 2010
G.f.: x*(3+5*x-3*x^2)/((1+x)*(1-x)^2). - Bruno Berselli, Feb 28 2012
E.g.f.: (1/4)*(5 - 12*exp(x) + (7 + 10*x)*exp(2*x))*exp(-x). - G. C. Greubel, Jul 15 2016
MATHEMATICA
LinearRecurrence[{1, 1, -1}, {3, 8, 8}, 30] (* Vincenzo Librandi, Feb 28 2012 *)
nxt[{n_, a_}]:={n+1, 5(n+1)-a+1}; Transpose[NestList[nxt, {1, 3}, 70]][[2]] (* Harvey P. Dale, Jan 23 2013 *)
PROG
(Magma) I:=[3, 8, 8]; [n le 3 select I[n] else Self(n-1)+Self(n-2)-Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 28 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 20 2009
STATUS
approved