OFFSET
0,7
COMMENTS
a(n) > 0 iff n is not a multiple of 10.
REFERENCES
G. Galperin and Y. J. Ionin (Proposers), and M. Reid (Solver), Problem 12034, Amer. Math. Monthly, 126:10, 950-951, Dec. 2019.
LINKS
Rémy Sigrist, Table of n, a(n) for n = 0..25000
PROG
(Python)
def A329792(n):
if n % 10:
m, s = 1, set('12345')
while not set(str(m*n)) <= s:
m += 1
return m
else:
return -1 # Chai Wah Wu, Dec 04 2019
CROSSREFS
KEYWORD
AUTHOR
N. J. A. Sloane, Dec 03 2019
STATUS
approved