OFFSET
0,2
LINKS
Ray Chandler, Table of n, a(n) for n = 0..1000
J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (pdf).
Joan Serra-Sagristà , Enumeration of lattice points in l_1 norm, Information Processing Letters, 76, no. 1-2 (2000), 39-44.
Index entries for linear recurrences with constant coefficients, signature (0, 2, 0, -1).
FORMULA
a(n)*a(n+3) = -24 + a(n+1)*a(n+2).
G.f.: (1+2x+10x^2+2x^3+x^4)/(1-x^2)^2 and a(2n)=12n for n>0, a(2n+1)=4n+2.
MAPLE
A035877 := proc(m) local k, t1; t1 := 2*binomial((2+2*m)/2-1, 1); if m mod 2 = 0 then t1 := t1+add(2^k*binomial(2, k)*binomial(m-1, k-1), k=0..2); fi; t1; end;
MATHEMATICA
f[m_, n_] := 2^(n - 1)*Binomial[(n + 2*m)/2 - 1, n - 1] + If[EvenQ[m], 2*n*Hypergeometric2F1[1 - m, 1 - n, 2, 2], 0]; f[0, _] = 1; Table[f[m, 2], {m, 0, 40}] (* Jean-François Alcover, Apr 18 2013, after Maple *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Joan Serra-Sagrista (jserra(AT)ccd.uab.es)
EXTENSIONS
Recomputed by N. J. A. Sloane, Nov 27 1998
Name edited by Andrey Zabolotskiy, Aug 29 2022
STATUS
approved