A075911 Third column of triangle A075500.
1, 30, 625, 11250, 188125, 3018750, 47265625, 728906250, 11133203125, 168996093750, 2554931640625, 38523925781250, 579858642578125, 8717878417968750, 130968170166015625, 1966522521972656250, 29517837677001953125, 442967564392089843750, 6646513462066650390625
Offset: 0
Links
- Colin Barker, Table of n, a(n) for n = 0..849
- Index entries for linear recurrences with constant coefficients, signature (30,-275,750).
Programs
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Mathematica
LinearRecurrence[{30,-275,750},{1,30,625},30] (* Harvey P. Dale, Oct 06 2017 *)
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PARI
Vec(1/((1-5*x)*(1-10*x)*(1-15*x)) + O(x^30)) \\ Colin Barker, Dec 11 2015
Formula
a(n) = (5^n - 8*10^n + 9*15^n)/2.
G.f.: 1/Product_{k=1..3} (1 - 5*k*x).
E.g.f.: (d^3/dx^3)(((exp(5*x)-1)/5)^3)/3! = (exp(5*x) - 8*exp(10*x) + 9*exp(15*x))/2!.
a(n) = 30*a(n-1) - 275*a(n-2) + 750*a(n-3) for n > 2. - Colin Barker, Dec 11 2015
Comments