OFFSET
0,2
LINKS
FORMULA
a(0) = 1, a(n) = 7*10^(n-1) for n>0.
a(n) = Sum_{k=0..n} A193722(n,k)*3^k.
MATHEMATICA
CoefficientList[Series[(1-3x)/(1-10x), {x, 0, 20}], x] (* or *) LinearRecurrence[ {10}, {1, 7}, 30] (* or *) Join[{1}, NestList[10#&, 7, 20]] (* Harvey P. Dale, Dec 18 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Oct 05 2011
STATUS
approved