OFFSET
1,1
LINKS
FORMULA
O.g.f.: z*(2-3*z)/(1-3*z)^2.
a(n) = -A287768(n+1,2).
a(n) = (n+1)*A000244(n-1). - Felix Fröhlich, Jun 19 2017
From Amiram Eldar, Jan 18 2021: (Start)
Sum_{n>=1} 1/a(n) = 9*log(3/2) - 3.
Sum_{n>=1} (-1)^(n+1)/a(n) = 3 - 9*log(4/3). (End)
MATHEMATICA
Table[(n + 1)*3^(n - 1), {n, 27}] (* Michael De Vlieger, Jun 23 2017 *)
LinearRecurrence[{6, -9}, {2, 9}, 40] (* Harvey P. Dale, Dec 16 2018 *)
PROG
(PARI) a(n) = (n+1)*3^(n-1) \\ Felix Fröhlich, Jun 19 2017
(PARI) Vec((z*(2-3*z)/(1-3*z)^2) + O(z^30)) \\ Felix Fröhlich, Jun 19 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Gregory Gerard Wojnar, Jun 17 2017
STATUS
approved