login
A133669
a(n) = a(n-1) - 49*a(n-2), a(0)=1, a(1)=7.
1
1, 7, -42, -385, 1673, 20538, -61439, -1067801, 1942710, 54264959, -40927831, -2699910822, -694447103, 131601183175, 165629091222, -6282828884353, -14398654354231, 293459960979066, 998994024336385, -13380544063637849, -62331251256120714
OFFSET
0,2
FORMULA
G.f.: (1+6*x)/(1-x+49*x^2) .
a(n) = Sum_{k=0..n} A133607(n,k)*7^k. - Philippe Deléham, Dec 30 2007
MATHEMATICA
LinearRecurrence[{1, -49}, {1, 7}, 20] (* or *) CoefficientList[ Series[ (1+6x)/(1-x+49x^2), {x, 0, 20}], x] (* Harvey P. Dale, Sep 08 2018 *)
CROSSREFS
Cf. A133607.
Sequence in context: A209071 A174224 A278571 * A205340 A304953 A293850
KEYWORD
easy,sign
AUTHOR
Philippe Deléham, Dec 28 2007
EXTENSIONS
More terms from Harvey P. Dale, Sep 08 2018
STATUS
approved