0,4

Let M_n be the n X n matrix of the following form [3 2 1 0 0 0 0 0 0 0 / 2 3 2 1 0 0 0 0 0 0 / 1 2 3 2 1 0 0 0 0 0 / 0 1 2 3 2 1 0 0 0 0 / 0 0 1 2 3 2 1 0 0 0 / 0 0 0 1 2 3 2 1 0 0 / 0 0 0 0 1 2 3 2 1 0 / 0 0 0 0 0 1 2 3 2 1 / 0 0 0 0 0 0 1 2 3 2 / 0 0 0 0 0 0 0 1 2 3]. Then for n>2 a(n) = det M_(n-2). - Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 20 2002

Largest possible size for the directed Cayley graph on two generators having diameter n-2. - Ralf Stephan, Apr 27 2003

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures}, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

C. K. Wong and D. Coppersmith, A combinatorial problem related to multimodule memory organizations, J. ACM 21 (1974), 392-402.

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures}, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

G.f.: x^2*(1+x)/((1-x)^2*(1-x^3)) - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Apr 01 2002

Euler transform of length 3 sequence [ 3, -1, 1]. - Michael Somos Sep 25 2006

G.f.: x^2*(1-x^2)/((1-x)^3*(1-x^3)). a(-n)=a(n). - Michael Somos Sep 25 2006

A000212:=(-1+z-2*z**2+z**3-2*z**4+z**5)/(z**2+z+1)/(z-1)**3; [Conjectured by S. Plouffe in his 1992 dissertation.]

(PARI) a(n)=n^2\3

Cf. A000290, A007590, A002620, A118015, A056827, A118013.

Adjacent sequences: A000209 A000210 A000211 this_sequence A000213 A000214 A000215

Sequence in context: A122539 A023660 A023562 this_sequence A094913 A020678 A014811

nonn

njas