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A028819
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Numbers n such that n^2 has digits in ascending order.
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3
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0, 1, 2, 3, 4, 5, 6, 7, 12, 13, 15, 16, 17, 34, 35, 37, 38, 67, 83, 106, 107, 116, 117, 167, 183, 334, 335, 337, 367, 383, 587, 667, 1633, 1667, 3334, 3335, 3337, 3367, 3383, 3667, 4833, 6667, 16667, 33334, 33335, 33337, 33367, 33667, 36667
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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LINKS
| P. De Geest, Palindromic Squares
Charles R Greathouse IV, Table of n, a(n) for n = 1..107
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MATHEMATICA
| okQ[n_]:=And@@(#[[2]]>=#[[1]]&/@Partition[IntegerDigits[n^2], 2, 1])
Select[Range[0, 50000], okQ] [From Harvey P. Dale, Jan 09 2011]
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PROG
| (PARI) mono(n)=n=eval(Vec(Str(n))); for(i=2, #n, if(n[i]<n[i-1], return(0))); 1
for(n=1, 1e5, if(mono(n^2), print1(n", "))) \\ Charles R Greathouse IV, Aug 22 2011
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CROSSREFS
| Cf. A028820.
Sequence in context: A032342 A023762 A032903 * A108948 A107818 A039952
Adjacent sequences: A028816 A028817 A028818 * A028820 A028821 A028822
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KEYWORD
| nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com)
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