A270471 Expansion of g.f. (1-3*x)/(1-7*x).
1, 4, 28, 196, 1372, 9604, 67228, 470596, 3294172, 23059204, 161414428, 1129900996, 7909306972, 55365148804, 387556041628, 2712892291396, 18990246039772, 132931722278404, 930522055948828, 6513654391641796, 45595580741492572, 319169065190448004, 2234183456333136028
Offset: 0
Links
- Colin Barker, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (7).
Crossrefs
Programs
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Mathematica
CoefficientList[Series[(1 - 3 x)/(1 - 7 x), {x, 0, 21}], x] (* Michael De Vlieger, Mar 18 2016 *) Join[{1},NestList[7#&,4,20]] (* Harvey P. Dale, Dec 21 2019 *) -
PARI
Vec((1-3*x)/(1-7*x) + O(x^30))
Formula
G.f.: (1-3*x)/(1-7*x).
a(n) = 7*a(n-1) for n>1.
a(n) = 4*7^(n-1) for n>0.
E.g.f.: (4*exp(7*x) + 3)/7. - Elmo R. Oliveira, Mar 25 2025
Comments