cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A201055 Composite numbers whose product of digits is 6.

Original entry on oeis.org

6, 16, 32, 116, 123, 132, 161, 213, 231, 312, 321, 611, 1116, 1132, 1161, 1312, 1611, 3112, 3211, 6111, 11116, 11123, 11132, 11231, 11312, 11611, 12131, 12311, 13112, 13211, 21113, 21131, 21311, 23111, 31112, 31211, 32111, 61111, 111116, 111123, 111132, 111161
Offset: 1

Views

Author

Jaroslav Krizek, Nov 26 2011

Keywords

Examples

			Number 123 is in sequence because 1*2*3 = 6.
		

Crossrefs

Cf. A199988 (numbers whose product of digits is 6).
Complement of A107692 (primes whose product of digits is 6) with respect to A199988.
Subsequence of A201020 (composite numbers whose multiplicative digital root is 6).

Programs

  • Python
    from sympy import prod, isprime
    from sympy.utilities.iterables import multiset_permutations
    def agen(maxdigits):
        for digs in range(1, maxdigits+1):
            for mp in multiset_permutations("1"*(digs-1) + "236", digs):
                if prod(map(int, mp)) == 6:
                    t = int("".join(mp))
                    if not isprime(t): yield t
    print(list(agen(6))) # Michael S. Branicky, Jun 16 2021
Previous Showing 11-11 of 11 results.