OFFSET
1,1
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (2,-1).
FORMULA
a(n) = 2*a(n-1) - a(n-2).
G.f.: x*(728820+180*x)/(1-x)^2.
E.g.f.: 180*(1 - (1 - 4050*x)*exp(x)). - G. C. Greubel, Jan 28 2022
MATHEMATICA
LinearRecurrence[{2, -1}, {728820, 1457820}, 40]
PROG
(Magma) I:=[728820, 1457820]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]];
(PARI) a(n)=729000*n-180 \\ Charles R Greathouse IV, Dec 23 2011
(Sage) [180*(4050*n -1) for n in (1..40)] # G. C. Greubel, Jan 28 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 17 2009
STATUS
approved