OFFSET
1,1
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*(22 + 59*x)/(1-x)^2.
E.g.f.: 59 - (59 - 81*x)*exp(x). - G. C. Greubel, Jun 26 2021
MATHEMATICA
LinearRecurrence[{2, -1}, {22, 103}, 50]
81*Range[50]-59 (* Harvey P. Dale, Jun 01 2020 *)
PROG
(Magma) I:=[22, 103]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..50]];
(PARI) a(n)=81*n-59 \\ Charles R Greathouse IV, Dec 23 2011
(Sage) [81*n - 59 for n in (1..50)] # G. C. Greubel, Jun 26 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Feb 16 2009
STATUS
approved