OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (7,-18,23,-16,6,-1).
FORMULA
a(n)=A124820(n)-A000217(n+1). G.f.: x^2(3-3x+x^2)/((1-x)^3*(1-4x+3x^2-x^3)). [From R. J. Mathar, Dec 15 2008]
a(1)=0, a(2)=3, a(3)=18, a(4)=73, a(5)=256, a(6)=844, a(n)=7*a(n-1)- 18*a(n-2)+ 23*a(n-3)-16*a(n-4)+6*a(n-5)-a (n-6). - Harvey P. Dale, Feb 07 2015
MATHEMATICA
lst={}; a=b=c=s=0; Do[c+=n+a; b+=n+c; a+=n+b; s+=a; AppendTo[lst, s], {n, 0, 2*4!}]; lst
Rest[CoefficientList[Series[x^2(3-3x+x^2)/((1-x)^3(1-4x+3x^2-x^3)), {x, 0, 40}], x]] (* Harvey P. Dale, Mar 11 2011 *)
LinearRecurrence[{7, -18, 23, -16, 6, -1}, {0, 3, 18, 73, 256, 844}, 30] (* Harvey P. Dale, Feb 07 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Dec 14 2008
STATUS
approved