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.

A201055 Composite numbers whose product of digits is 6.

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%I A201055 #11 Jun 16 2021 10:17:39
%S A201055 6,16,32,116,123,132,161,213,231,312,321,611,1116,1132,1161,1312,1611,
%T A201055 3112,3211,6111,11116,11123,11132,11231,11312,11611,12131,12311,13112,
%U A201055 13211,21113,21131,21311,23111,31112,31211,32111,61111,111116,111123,111132,111161
%N A201055 Composite numbers whose product of digits is 6.
%H A201055 Michael S. Branicky, <a href="/A201055/b201055.txt">Table of n, a(n) for n = 1..10860</a> (all terms with <= 32 digits)
%e A201055 Number 123 is in sequence because 1*2*3 = 6.
%o A201055 (Python)
%o A201055 from sympy import prod, isprime
%o A201055 from sympy.utilities.iterables import multiset_permutations
%o A201055 def agen(maxdigits):
%o A201055     for digs in range(1, maxdigits+1):
%o A201055         for mp in multiset_permutations("1"*(digs-1) + "236", digs):
%o A201055             if prod(map(int, mp)) == 6:
%o A201055                 t = int("".join(mp))
%o A201055                 if not isprime(t): yield t
%o A201055 print(list(agen(6))) # _Michael S. Branicky_, Jun 16 2021
%Y A201055 Cf. A199988 (numbers whose product of digits is 6).
%Y A201055 Complement of A107692 (primes whose product of digits is 6) with respect to A199988.
%Y A201055 Subsequence of A201020 (composite numbers whose multiplicative digital root is 6).
%K A201055 nonn,base
%O A201055 1,1
%A A201055 _Jaroslav Krizek_, Nov 26 2011