OFFSET
1,2
COMMENTS
Also structured deltoidal icositetrahedral numbers (vertex structure 7) (cf. A100161 = alternate vertex).
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..5000
FORMULA
a(n) = (1/6)*(42*n^3 - 54*n^2 + 18*n).
G.f.: x*(1 + 22*x + 19*x^2)/(1-x)^4. - Colin Barker, Jan 19 2012
PROG
(Magma) [(1/6)*(42*n^3-54*n^2+18*n): n in [1..40]]; // Vincenzo Librandi, Jul 24 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
James A. Record (james.record(AT)gmail.com), Nov 07 2004
STATUS
approved