OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..5000
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
a(n) = (1/3)*n*(17*n^2 - 18*n + 4).
G.f.: x*(1 + 20*x + 13*x^2)/(1-x)^4. - Colin Barker, Feb 12 2012
From Elmo R. Oliveira, Aug 05 2025: (Start)
E.g.f.: exp(x)*x*(17*x^2 + 33*x + 3)/3.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n > 4. (End)
MATHEMATICA
LinearRecurrence[{4, -6, 4, -1}, {1, 24, 103, 272}, 50] (* Paolo Xausa, Aug 06 2025 *)
PROG
(Magma) [(1/6)*(34*n^3-36*n^2+8*n): n in [1..40]]; // Vincenzo Librandi, Jul 19 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
James A. Record (james.record(AT)gmail.com), Nov 07 2004
STATUS
approved
