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A081338
a(n) = (9^n + 5^n)/2.
2
1, 7, 53, 427, 3593, 31087, 273533, 2430547, 21718673, 194686807, 1748275013, 15714943867, 141336838553, 1271543265727, 11441447985293, 102960824836387, 926586388371233, 8338972319559847, 75049224997132373, 675435395579660107
OFFSET
0,2
COMMENTS
Binomial transform of A081337. 7th binomial transform of (1,0,4,0,16,0,64,....).
FORMULA
a(n) = 14*a(n-1)-45*a(n-2), a(0)=1, a(1)=7.
G.f.: (1-7*x)/((1-5*x)*(1-9*x)).
E.g.f.: exp(7*x) * cosh(2*x).
MATHEMATICA
CoefficientList[Series[(1 - 7 x) / ((1 - 5 x) (1 - 9 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Aug 08 2013 *)
PROG
(Magma) [(9^n+5^n)/2: n in [0..25]]; // Vincenzo Librandi, Aug 08 2013
CROSSREFS
Sequence in context: A015561 A133588 A163306 * A367937 A142981 A350252
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Mar 18 2003
STATUS
approved