OFFSET
0,2
COMMENTS
The altitude h(n) = a(n)/A001844(n) of the (A005408(n), A046092(n) and A001844(n)) rectangular triangle is an irreducible fraction. - Ralf Steiner, Feb 25 2020
In this case, area A = a(n)/2 = A055112(n). - Bernard Schott, Feb 27 2020
LINKS
S. P. Borgatti and M. G. Everett, Notions of Position in Social Network Analysis, Sociological Methodology, 22 (1992), 1-35.
C. Purcell and P. Rombach, Role colouring graphs in hereditary classes, arXiv:1802.10180 [math.CO], 2018.
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
a(n) = 12*A000330(n).
G.f.: 12*x*(1+x)/(1-x)^4. - Colin Barker, Mar 12 2018
From Ralf Steiner, Feb 27 2020: (Start)
a(n) = 2*n*A000384(n+1).
(End)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Christopher Purcell, Mar 12 2018
EXTENSIONS
Edited by N. J. A. Sloane, Aug 01 2019
STATUS
approved