OFFSET
1,3
COMMENTS
Extended to a(1)-a(3) using the formula/recurrence.
LINKS
Eric Weisstein's World of Mathematics, Graph Path
Eric Weisstein's World of Mathematics, Wheel Graph
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = (n - 1)*(2*n^3 - 12*n^2 + 43*n - 48)/6.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5).
G.f.: x^2*(1 + 4*x - 5*x^2 + 8*x^3)/(1 - x)^5.
MATHEMATICA
Table[(n - 1) (2 n^3 - 12 n^2 + 43 n - 48)/6, {n, 20}]
LinearRecurrence[{5, -10, 10, -5, 1}, {0, 1, 9, 30, 78}, 20]
CoefficientList[Series[x (1 + 4 x - 5 x^2 + 8 x^3)/(1 - x)^5, {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Sep 07 2017
STATUS
approved