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A348549
Number of positive integers with n digits that are the product of two integers ending with 8.
2
0, 1, 14, 195, 2200, 24013, 255969, 2687317, 27934809, 288342379, 2960920297, 30285890402, 308834717932, 3141625339760, 31895159990436
OFFSET
1,3
COMMENTS
a(n) is the number of n-digit numbers in A348548.
FORMULA
a(n) < A052268(n).
Conjecture: lim_{n->infinity} a(n)/a(n-1) = 10.
PROG
(Python)
def a(n):
lo, hi = 10**(n-1), 10**n
return len(set(a*b for a in range(8, hi//8+1, 10) for b in range(a, hi//a+1, 10) if lo <= a*b < hi))
print([a(n) for n in range(1, 9)]) # Michael S. Branicky, Oct 22 2021
CROSSREFS
Cf. A346509 (ending with 1), A346629 (ending with 2), A346952 (ending with 3), A347255 (ending with 4), A337855 (ending with 5), A337856 (ending with 6), A348055 (ending with 7).
Sequence in context: A275084 A086946 A158530 * A171319 A007655 A208383
KEYWORD
nonn,base,hard,more
AUTHOR
Stefano Spezia, Oct 22 2021
EXTENSIONS
a(9)-a(10) from Michael S. Branicky, Oct 22 2021
a(11)-a(15) from Martin Ehrenstein, Nov 06 2021
STATUS
approved