OFFSET
1,2
LINKS
Kevin Ryde, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = floor(n / 5^floor(log_5(n))).
G.f.: (x + Sum_{k>=0} Sum_{d=2..4} (x^(d*5^k)-x^(5^(k+1))) )/(1-x).
MATHEMATICA
IntegerDigits[#, 5][[1]]&/@Range[100] (* Harvey P. Dale, Sep 04 2021 *)
PROG
(PARI) a(n) = n\5^logint(n, 5);
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Kevin Ryde, Nov 28 2020
STATUS
approved