OFFSET
1,2
LINKS
Vincenzo Librandi,Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
a(n) = (1/6)*(3*n^4 - 8*n^3 + 9*n^2 + 2*n).
G.f.: x*(1 - x + 9*x^2 + 3*x^3)/(1-x)^5. -Colin Barker, Jun 08 2012
FromElmo R. Oliveira, Sep 09 2025: (Start)
E.g.f.: exp(x)*x*(3*x^3 + 10*x^2 + 6*x + 6)/6.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n > 5. (End)
EXAMPLE
There are no 1- or 2-gonal anti-prisms, so 1 and (2n) are used as the first and second terms since all the sequences begin as such.
PROG
(Magma) [(1/6)*(3*n^4-8*n^3+9*n^2+2*n): n in [1..40]]; //Vincenzo Librandi, Aug 03 2011
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
James A. Record (james.record(AT)gmail.com)
STATUS
approved