OFFSET
2,1
COMMENTS
The sequence is the column corresponding to k=2 in A090657. - Geoffrey Critzer, Mar 06 2009
LINKS
Stefano Spezia, Table of n, a(n) for n = 2..3200
Index entries for linear recurrences with constant coefficients, signature (9,-33,63,-66,36,-8).
FORMULA
a(n) = C(n, 2) * (2^n - 2).
O.g.f.: (4x^2/(1-2x)^3) - (2x^2/(1-x)^3). - Geoffrey Critzer, Mar 06 2009
E.g.f.: exp(x)*(2*exp(x) - 1)*x^2. - Stefano Spezia, May 06 2023
MATHEMATICA
Table[ Binomial[n, 2]*(2^n - 2), {n, 2, 30}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Sharon Sela (sharonsela(AT)hotmail.com), Mar 29 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Apr 17 2002
STATUS
approved