OFFSET
0,11
COMMENTS
a(10^n) = 10^n. a{(10^n-1)/9} = n*((10^n-1)/9).
a(0)=1 since C(0,0)=1.
EXAMPLE
a(12) = C(12,1)+C(12,2) = 12+66 = 78.
a(111) = 333.
MATHEMATICA
f[n_] := Plus @@ Binomial[n, IntegerDigits[n]]; Table[ f[n], {n, 41}] (* Robert G. Wilson v *)
CROSSREFS
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Aug 17 2005
EXTENSIONS
Edited, corrected and extended by Robert G. Wilson v, Aug 19 2005
STATUS
approved