OFFSET
1,2
COMMENTS
Also, this is a row of the square array A255741.
PROG
(PARI) a(n) = sum(k=1, n, if (k==1, 1, 11*10^(hammingweight(k-1)-1)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Mar 05 2015
EXTENSIONS
More terms from Michel Marcus, Mar 19 2015
STATUS
approved