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A235717
Squares which have one or more occurrences of exactly two different digits.
11
16, 25, 36, 49, 64, 81, 100, 121, 144, 225, 400, 441, 484, 676, 900, 1444, 7744, 10000, 11881, 29929, 40000, 44944, 55225, 69696, 90000, 1000000, 4000000, 9000000, 9696996, 100000000, 400000000, 900000000, 6661661161, 10000000000, 40000000000, 90000000000
OFFSET
1,1
COMMENTS
The first term having a repeated digit is 100.
This sequence is the same as A018885, except that A018885 has four additional leading terms.
FORMULA
a(n) = A016069(n)^2.
EXAMPLE
69696 is in the sequence because 69696 = 264^2 and 69696 contains exactly two different digits: 6 and 9.
PROG
(PARI) s=[]; for(n=1, 10000, if(#vecsort(eval(Vec(Str(n^2))), , 8)==2, s=concat(s, n^2))); s
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Colin Barker, Jan 15 2014
STATUS
approved