OFFSET
1,2
COMMENTS
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) = n^2 - 2n + C(n,2)^2 + 1
a(n) = (n-1)^2*(n^2+4)/4. - Vincenzo Librandi, Sep 09 2011
G.f.: x^2*(2+3*x+x^3)/(1-x)^5. - Colin Barker, Feb 15 2012
a(n)=5*a(n-1)-10*a(n-2)+ 10*a(n-3)- 5*a(n-4)+a(n-5), n>5. - Harvey P. Dale, Oct 16 2012
MAPLE
A117717 := proc(n)
(n-1)^2*(n^2+4)/4 ;
end proc:
seq(A117717(n), n=1..10) ; # R. J. Mathar, Sep 15 2013
MATHEMATICA
Table[n^2-2n+Binomial[n, 2]^2+1, {n, 40}] (* or *) LinearRecurrence[ {5, -10, 10, -5, 1}, {0, 2, 13, 45, 116}, 40] (* Harvey P. Dale, Oct 16 2012 *)
PROG
(Magma)[(n-1)^2*(n^2+4)/4: n in [1..40]]; // Vincenzo Librandi, Sep 09 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Patricia A. Carey and Anant Godbole, Apr 13 2006
EXTENSIONS
More terms from Harvey P. Dale, Oct 16 2012
STATUS
approved