3,2

For n >= 1 a(n) is also the determinant of the n-3 X n-3 matrix with 4's on the diagonal and 1's elsewhere. - Ahmed Fares (ahmedfares(AT)my-deja.com), May 06 2001

a(n+3)=det(M(n)) where M(n) is the n X n matrix with m(i,i)=4, m(i,j)=i/j for i != j. - Benoit Cloitre (benoit7848c(AT)orange.fr), Feb 01 2003

Main diagonal of array defined by m(1,j)=j; m(i,1)=i and m(i,j)=m(i-1,j)+2*m(i-1,j-1) - Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 13 2003

a(n+3) is the number of words of length n on {A, B, C, D} with no D appearing anywhere to the right of an A. - Rob Pratt (Rob.Pratt(AT)sas.com), Aug 04 2004

Number of spanning trees in the graph S_{n-2} X P_2 (S_k = the star graph on k nodes) (conjectured).

a(n+3) = sum of the n-th row of A112626. - Ross La Haye (rlahaye(AT)new.rr.com), Jan 11 2006

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.

G. Kreweras, Complexite et circuits Euleriens dans la sommes tensorielles de graphes, J. Combin. Theory, B 24 (1978), 202-212.

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.: (1-2x)/(1-3x)^2 - Paul Barry (pbarry(AT)wit.ie), Feb 27 2003

A006234:=-(-1+2*z)/(3*z-1)**2; [Conjectured by S. Plouffe in his 1992 dissertation.]

Binomial transform of A001792.

Cf. A036290, A050914.

Adjacent sequences: A006231 A006232 A006233 this_sequence A006235 A006236 A006237

Sequence in context: A057332 A071719 A090326 this_sequence A094821 A071723 A001559

nonn,easy

njas