OFFSET
1,2
PROG
(PARI) a(n)=4*sum(i=0, n-1, (n-i)*3^hammingweight(i)) \\ Charles R Greathouse IV, Aug 25 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Jun 14 2009
EXTENSIONS
More terms from Max Alekseyev, Dec 12 2011
STATUS
approved