OFFSET
0,9
FORMULA
a(7*n) = 50^(n-1) for n > 0.
a(n) = Sum_{k=0..floor(n/7)} 49^k * binomial(n/7-1,k).
a(n) == 1 (mod 7).
PROG
(PARI) a(n) = sum(k=0, n\7, 49^k*binomial(n/7-1, k));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Jun 07 2024
STATUS
approved