OFFSET
1,1
COMMENTS
LINKS
Colin Barker, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,1,-1).
FORMULA
a(n) = a(n-1) + a(n-2) - a(n-3), n >= 4.
G.f.: x*(17 + 6*x + 7*x^2)/((1 + x)*(1 - x)^2).
a(n) = a(n-2) + 30.
a(n) = 10*(3*n - 2) - a(n-1).
From Colin Barker, Jan 24 2016: (Start)
a(n) = (30*n - 9*(-1)^n - 5)/2 for n>0.
a(n) = 15*n - 7 for n>0 and even.
a(n) = 15*n + 2 for n odd.
(End)
E.g.f.: 7 + ((30*x - 5)*exp(x) - 9*exp(-x))/2. - David Lovler, Sep 10 2022
MATHEMATICA
LinearRecurrence[{1, 1, -1}, {17, 23, 47}, 52]
PROG
(Magma) [n: n in [0..773] | n mod 30 in {17, 23}];
(PARI) Vec(x*(17 + 6*x + 7*x^2)/((1 + x)*(1 - x)^2) + O(x^53))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Arkadiusz Wesolowski, Jan 23 2016
STATUS
approved