A348549 Number of positive integers with n digits that are the product of two integers ending with 8.
0, 1, 14, 195, 2200, 24013, 255969, 2687317, 27934809, 288342379, 2960920297, 30285890402, 308834717932, 3141625339760, 31895159990436
Offset: 1
Crossrefs
Programs
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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
Formula
a(n) < A052268(n).
Conjecture: lim_{n->infinity} a(n)/a(n-1) = 10.
Extensions
a(9)-a(10) from Michael S. Branicky, Oct 22 2021
a(11)-a(15) from Martin Ehrenstein, Nov 06 2021
Comments