

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
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OFFSET

1,3


COMMENTS

a(n) is the number of ndigit numbers in A348548.


LINKS

Table of n, a(n) for n=1..15.


FORMULA

a(n) < A052268(n).
Conjecture: lim_{n>infinity} a(n)/a(n1) = 10.


PROG

(Python)
def a(n):
lo, hi = 10**(n1), 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. A052268, A348548.
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
Adjacent sequences: A348546 A348547 A348548 * A348550 A348551 A348552


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



