OFFSET
0,2
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (10, -45, 120, -210, 252, -210, 120, -45, 10, -1).
FORMULA
Appears to satisfy a 9-degree polynomial. - Ralf Stephan, Mar 07 2004
Empirical g.f.: (x+1)*(93*x^8+620*x^7-848*x^6+516*x^5-150*x^4+20*x^3+8*x^2-4*x+1) / (x-1)^10. - Colin Barker, Jul 07 2013
Above conjectures confirmed by later additions of b-file from Andrew Howroyd and program from Jean-François Alcover with connection to A302997. - Ray Chandler, Jun 27 2024
a(n) = 1 +1126/315*n +84668/2835*n^3 -418/45*n^2 +2152/135*n^5 -64/15*n^6 +584/945*n^7 -2/45*n^8 -152/5*n^4 +4/2835*n^9. - R. J. Mathar, Aug 03 2025
MATHEMATICA
a[n_] := SeriesCoefficient[1/(1-x) Sum[x^(i^2), {i, -3, 3}]^n, {x, 0, 9}];
a /@ Range[0, 26] (* Jean-François Alcover, Sep 29 2019, from A302997 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved