A081627 2*7^n-5^n.
1, 9, 73, 561, 4177, 30489, 219673, 1568961, 11138977, 78754089, 555184873, 3905825361, 27438433777, 192557317689, 1350342630073, 9464605441761, 66313273248577, 464498088521289, 3253012498555273, 22778716884418161
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (12,-35).
Programs
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Magma
[2*7^n-5^n: n in [0..25]]; // Vincenzo Librandi, Aug 09 2013
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Mathematica
CoefficientList[Series[(1 - 3 x) / ((1 - 5 x) (1 - 7 x)), {x, 0, 40}], x] (* Vincenzo Librandi, Aug 09 2013 *)
Formula
G.f.: (1-3*x)/((1-5*x)*(1-7*x)).
E.g.f. 2*exp(7*x)-exp(5*x).
Comments