cp's OEIS Frontend

A218013 Numbers that divide the product of the nonzero digits (in base 10) of their square.

%I A218013 #46 May 04 2019 03:40:38
%S A218013 1,2,3,5,6,8,28,36,42,54,75,192,216,288,486,525,648,768,864,882,1728,
%T A218013 2160,3024,6048,6075,7056,7680,17280,18144,20736,30240,40824,56448,
%U A218013 60480,61236,62208,64512,84672,122472,138915,150528,387072,408240,497664,622080
%N A218013 Numbers that divide the product of the nonzero digits (in base 10) of their square.
%H A218013 David A. Corneth, <a href="/A218013/b218013.txt">Table of n, a(n) for n = 1..10919</a> (first 473 terms from Chai Wah Wu; terms <= 10^100)
%e A218013 For n=5, n^2 is 25; the product of the digits of 25 is 2 * 5 = 10, which is divisible by n=5.
%o A218013 (PARI) isok(n) = digs = digits(n^2); (prod(i=1, #digs, if (digs[i], digs[i], 1)) % n) == 0; \\ _Michel Marcus_, Aug 12 2013
%o A218013 (Python)
%o A218013 from operator import mul
%o A218013 from functools import reduce
%o A218013 from gmpy2 import t_mod, mpz
%o A218013 A218013 = [n for n in range(1,10**6) if not t_mod(reduce(mul,(mpz(d) for d in str(n**2) if d != '0')),n)] # _Chai Wah Wu_, Aug 23 2014
%Y A218013 Cf. A002473.
%Y A218013 Related to A218072. Subsets of this sequence include A218029 and A218030.
%K A218013 nonn,base
%O A218013 1,2
%A A218013 _Nels Olson_, Oct 18 2012