0,2

Number of nodes degree 10 in virtual, optimal chordal graphs of diameter d(G)=n - S. Bujnowski & B. Dubalski (slawb(AT)atr.bydgoszcz.pl), Mar 07 2002

If Y_i (i=1,2,3,4,5) are 2-blocks of a (n+5)-set X then a(n-5) is the number of 10-subsets of X intersecting each Y_i (i=1,2,3,4,5). - Milan R. Janjic (agnus(AT)blic.net), Oct 28 2007

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.

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 81.

R. G. Stanton and D. D. Cowan, Note on a "square" functional equation, SIAM Rev., 12 (1970), 277-279.

T. D. Noe, Table of n, a(n) for n=0..1000

Milan Janjic, Two Enumerative Functions

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.

Index entries for crystal ball sequences

J. H. Conway and N. J. A. Sloane, Low-Dimensional Lattices VII: Coordination Sequences, Proc. Royal Soc. London, A453 (1997), 2369-2389 (Abstract, pdf, ps).

G.f.: (1+x)^5 /(1-x)^6.

a(n)=(4*n^5+10*n^4+40*n^3+50*n^2+46*n+15)/15 - S. Bujnowski & B. Dubalski (slawb(AT)atr.bydgoszcz.pl), Mar 07 2002

a(5)=1683, (4*5^5+10*5^4+40*5^3+50*5^2+46*5+15)/15=(12500+6250+5000+230+15)/15=25245/15=1683

for n from 1 to k do eval((4*n^5+10*n^4+40*n^3+50*n^2+46*n+15)/15) od;

A001847:=(z+1)**5/(z-1)**6; [Conjectured by S. Plouffe in his 1992 dissertation.]

Sequence in context: A002650 A060884 A141935 this_sequence A089764 A023298 A106992

Adjacent sequences: A001844 A001845 A001846 this_sequence A001848 A001849 A001850

nonn,easy

njas