OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (1,6,-6,-15,15,20,-20,-15,15,6,-6,-1,1).
FORMULA
G.f.: -(x^12 +24*x^11 +2994*x^10 +5112*x^9 +54959*x^8 +35824*x^7 +129852*x^6 +35824*x^5 +54959*x^4 +5112*x^3 +2994*x^2 +24*x +1)/((x -1)^7*(x +1)^6). - Colin Barker, Nov 16 2012
a(n) = A015221(n)^2. - R. J. Mathar, Jul 30 2016
Sum_{n>=0} 1/a(n) = (171/4 - 18*sqrt(2))*Pi^2 - 54*Pi. - Amiram Eldar, Mar 07 2022
MATHEMATICA
CoefficientList[Series[-(x^12+24x^11+2994x^10+5112x^9+54959x^8+35824x^7+ 129852x^6+ 35824x^5+54959x^4+5112x^3+2994x^2+24x+1)/((x-1)^7(x+1)^6), {x, 0, 30}], x] (* or *) LinearRecurrence[ {1, 6, -6, -15, 15, 20, -20, -15, 15, 6, -6, -1, 1}, {1, 25, 3025, 8281, 81225, 148225, 670761, 1030225, 3186225, 4447881, 10962721, 14402025, 30525625}, 30](* Harvey P. Dale, Feb 17 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved