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Positive numbers of the form u * v where the decimal representations of u and of v have the same number of digits d for d = 0..9.
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%I #10 Jan 13 2020 18:27:09

%S 1,4,9,16,25,36,49,64,81,100,121,144,169,196,225,252,256,289,324,361,

%T 400,403,441,484,529,574,576,625,676,729,736,765,784,841,900,961,976,

%U 1008,1024,1089,1156,1207,1225,1296,1300,1369,1444,1458,1462,1521,1600

%N Positive numbers of the form u * v where the decimal representations of u and of v have the same number of digits d for d = 0..9.

%C In other words, the terms of this sequence are squares or the products of two decimal anagrams.

%C Leading zeros are ignored.

%C If m belongs to the sequence, then 100*m also belongs to the sequence.

%H Rémy Sigrist, <a href="/A331221/b331221.txt">Table of n, a(n) for n = 1..10000</a>

%e The numbers 12 and 21 are decimal anagrams, so 252 = 12*21 belongs to the sequence.

%o (PARI) is(n, base=10) = fordiv (n,d, if (vecsort(digits(d,base))==vecsort(digits(n/d,base)), return (1))); return (0)

%Y Cf. A331219 (binary analog), A331220 (ternary analog), A331270, A331271.

%K nonn,base

%O 1,2

%A _Rémy Sigrist_, Jan 12 2020