OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
FORMULA
a(n) = (625n^5-11250n^4+98875n^3-515250n^2+1566016n-2194944)/24, n>=16.
G.f.: x*(2*x^20 -4*x^19 +8*x^18 -12*x^17 -48*x^16 +140*x^15 -158*x^14 +208*x^13 +134*x^12 -932*x^11 +1048*x^10 -182*x^9 +436*x^8 +396*x^7 -32*x^6 +1288*x^5 +668*x^4 +72*x^3 +86*x^2 +6*x+1)/(x-1)^6. - Vaclav Kotesovec, Mar 25 2010
MATHEMATICA
CoefficientList[Series[(2 x^20 - 4 x^19 + 8 x^18 - 12 x^17 - 48 x^16 + 140 x^15 - 158 x^14 + 208 x^13 + 134 x^12 - 932 x^11 + 1048*x^10 -182*x^9+ 436 * x^8 + 396 x^7 - 32 x^6 + 1288 * x^5 + 668 * x^4 + 72 * x^3 + 86 * x^2 + 6 * x + 1) / (x - 1)^6, {x, 0, 50}], x] (* Vincenzo Librandi, May 27 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vaclav Kotesovec, Jan 29 2010
STATUS
approved