OFFSET
0,2
COMMENTS
The given closed-form formula is provable.
FORMULA
a(n) = n*2^(3*n-1) + 3*n*2^(n-2)*binomial(2*n, n).
MATHEMATICA
Table[n*2^(3n-1)+3n*2^(n-2) Binomial[2n, n], {n, 0, 20}] (* Harvey P. Dale, Nov 24 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Ognjen Dragoljevic, Dec 26 2017
STATUS
approved