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) = (1/6)*(80*n^3 - 102*n^2 + 28*n).
From Jaume Oliver Lafont, Sep 08 2009: (Start)
a(n) = ((n-1)+1)*(5*(n-1)+3)*(8*(n-1)+1)/3.
G.f.: x*(1 + 44*x + 35*x^2)/(1-x)^4. (End)
From Elmo R. Oliveira, Aug 05 2025: (Start)
E.g.f.: exp(x)*x*(40*x^2 + 69*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, 48, 221, 600}, 40] (* Harvey P. Dale, Jan 07 2026 *)
PROG
(Magma) [((n-1)+1)*(5*(n-1)+3)*(8*(n-1)+1)/3: 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
