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.

29, 1674, 136854, 12082393, 1136370471, 111392993465

Offset

1,1

Links

Table of n, a(n) for n=1..6.

Prog

(PARI) See A370678.
(Python)
def A370679(n):
    a = 10**(n-1)
    b, c = 10*a, 0
    for x in range(a, b):
        s = set(str(x))
        for y in range(x, b):
            if len(s|set(str(y))) == len(set(str(x*y))):
                c += 1
    return c # Chai Wah Wu, Feb 28 2024

Crossrefs

Cf. A370675, A370676, A370678, A370680.

Sequence in context: A091994 A126555 A028478 * A042627 A042624 A190826

Adjacent sequences: A370676 A370677 A370678 * A370680 A370681 A370682

Keyword

nonn,base,more

Author

Hugo Pfoertner, Feb 26 2024

Extensions

a(6) from Martin Ehrenstein, Feb 29 2024

Status

approved