OFFSET
1,1
COMMENTS
Extended to a(1)-a(2) using the formula.
LINKS
Eric Weisstein's World of Mathematics, Clique
Eric Weisstein's World of Mathematics, Sun Graph
Index entries for linear recurrences with constant coefficients, signature (4, -5, 2).
FORMULA
a(n) = 2^n + 4*n.
a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3).
G.f.: -2*x*(3 - 6*x + x^2)/((-1 + x)^2*(-1 + 2*x)).
MATHEMATICA
Table[2^n + 4 n, {n, 20}]
LinearRecurrence[{4, -5, 2}, {6, 12, 20}, 20]
CoefficientList[Series[-2 (3 - 6 x + x^2)/((-1 + x)^2 (-1 + 2 x)), {x, 0, 20}], x]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Nov 29 2017
STATUS
approved