cp's OEIS Frontend

A370679 a(n) is the number of pairs x <= y of n-digit numbers such that the number of distinct digits in their product is the same as in their concatenation.

%I A370679 #15 Feb 29 2024 13:01:48
%S A370679 29,1674,136854,12082393,1136370471,111392993465
%N A370679 a(n) is the number of pairs x <= y of n-digit numbers such that the number of distinct digits in their product is the same as in their concatenation.
%o A370679 (PARI) See A370678.
%o A370679 (Python)
%o A370679 def A370679(n):
%o A370679     a = 10**(n-1)
%o A370679     b, c = 10*a, 0
%o A370679     for x in range(a,b):
%o A370679         s = set(str(x))
%o A370679         for y in range(x,b):
%o A370679             if len(s|set(str(y))) == len(set(str(x*y))):
%o A370679                 c += 1
%o A370679     return c # _Chai Wah Wu_, Feb 28 2024
%Y A370679 Cf. A370675, A370676, A370678, A370680.
%K A370679 nonn,base,more
%O A370679 1,1
%A A370679 _Hugo Pfoertner_, Feb 26 2024
%E A370679 a(6) from _Martin Ehrenstein_, Feb 29 2024