OFFSET
1,2
COMMENTS
Also partial sums of A257143. - Reinhard Zumkeller, Apr 17 2015
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).
FORMULA
a(1)=1, a(2n) = a(2n-1)+2n-1, a(2n+1)=a(2n)+3n; a(n) = A111710(n-1)+1. - Franklin T. Adams-Watters, May 01 2006
From Chai Wah Wu, Mar 05 2021: (Start)
a(n) = a(n-1) + 2*a(n-2) - 2*a(n-3) - a(n-4) + a(n-5) for n > 5.
G.f.: x*(-x^4 - x^3 - x^2 - x - 1)/((x - 1)^3*(x + 1)^2). (End)
a(n) = (10*n*(n-1) + (-1)^n*(1-2*n)+15)/16. - Eric Simon Jacob, Jun 11 2022
MATHEMATICA
LinearRecurrence[{1, 2, -2, -1, 1}, {1, 2, 5, 8, 14}, 60] (* Harvey P. Dale, Jun 21 2023 *)
PROG
(Haskell)
a111711 n = a111711_list !! (n-1)
a111711_list = 1 : zipWith (+) a111711_list a080512_list
-- Reinhard Zumkeller, Apr 17 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Aug 24 2005
EXTENSIONS
More terms from Franklin T. Adams-Watters, May 01 2006
STATUS
approved