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A106497
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Numbers whose square is the concatenation of two identical numbers, i.e. of form NN.
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46
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36363636364, 45454545455, 54545454546, 63636363637, 72727272728, 81818181819, 90909090910, 428571428571428571429, 571428571428571428572, 714285714285714285715, 857142857142857142858
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| For the corresponding numbers N see A102567.
Numbers of the form j*(10^d+1)/k where 10^d+1 == 0 (mod k^2) and k/sqrt(10) < j < k. - David W. Wilson (davidwwilson(AT)comcast.net), Nov 09 2006
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REFERENCES
| R. Ondrejka, Problem 1130: Biperiod Squares, Journal of Recreational Mathematics, Vol. 14:4 (1981-82), 299. Solution by F. H. Kierstead, Jr., JRM, Vol. 15:4 (1982-83), 311-312.
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LINKS
| David W. Wilson, Table of n, a(n) for n = 1..1098
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EXAMPLE
| 63636363637 is in the sequence because 63636363637^2 = 4049586776940495867769 is 40495867769 written twice.
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CROSSREFS
| Cf. A092118, A102567.
Sequence in context: A115502 A022262 A116279 * A204097 A178221 A038832
Adjacent sequences: A106494 A106495 A106496 * A106498 A106499 A106500
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KEYWORD
| base,nonn
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AUTHOR
| Lekraj Beedassy (blekraj(AT)yahoo.com), May 04 2005
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EXTENSIONS
| a(7) from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 06 2005
More terms from David W. Wilson (davidwwilson(AT)comcast.net), Nov 05 2006
Reference and cross-references added by William Rex Marshall (w.r.marshall(AT)actrix.co.nz), Nov 12 2010
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