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A066733
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Numbers such that the nonzero product of the digits of its square is also a square.
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1
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1, 2, 3, 7, 12, 17, 21, 38, 88, 106, 107, 108, 109, 117, 122, 128, 129, 141, 146, 164, 168, 171, 173, 178, 191, 196, 204, 206, 207, 208, 209, 212, 221, 222, 236, 263, 276, 278, 288, 306, 342, 359, 364, 367, 372, 377, 394, 432, 463, 478, 479, 518, 537, 538
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
| 17 is in the sequence because the square of 17 is 289 and 2*8*9 = 144 = 12^2.
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MATHEMATICA
| Do[a = Apply[Times, IntegerDigits[n^2]]; If[ a != 0 && IntegerQ[a^(1/2)], Print[n]], {n, 1, 10^4} ]
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PROG
| (PARI) ProdD(x)= { local(p=1); while (x>9 && p>0, p*=x%10; x\=10); return(p*x) } { n=0; for (m=1, 10^10, if (issquare(p=ProdD(m^2)) && p > 0, write("b066733.txt", n++, " ", m); if (n==1000, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Mar 20 2010]
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CROSSREFS
| Cf. A067071.
Sequence in context: A080140 A019568 A128458 * A049623 A061577 A006488
Adjacent sequences: A066730 A066731 A066732 * A066734 A066735 A066736
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KEYWORD
| nonn,base
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AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 15 2002
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