OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..90
FORMULA
a(n) = [x^(7^n)] (Sum_{j=0..6*n+1} x^(7^j))^(6*n+1).
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 09 2017
STATUS
approved