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Search: id:A115439
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| A115439 |
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Numbers n such that the square of n is the concatenation of two numbers k and k+5. |
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+0
12
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| 4, 7, 45, 56, 38163, 61838, 83618, 346980, 653021, 950051, 8647555, 9534265, 8167822283, 9007920992, 9209900792, 9950000501, 4737445289221, 4990568257187, 5009431742814, 5262554710780, 8373808925585
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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All numbers of the form f(n)=9(n).5.0(2n).5.0(n-1).1 where n>0 are in the sequence because if k(n)=9(n).0(n).25.0(n-1).9(n).6 then f(n)^2=k(n).(k(n)+5). For example f(2)=9950000501; k(2)=9900250996 and f(2)^2=9950000501^2=9900250996.9900251001 =k(2).(k(2)+5). - Farideh Firoozbakht (mymontain(AT)yahoo.com), Nov 26 2006
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EXAMPLE
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38163^2 = 14564_14569.
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CROSSREFS
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Cf. A030467, A106497, A115428, A115427, A115438, A115440, A115441, A115442, A115443, A115444, A115445, A115446, A115447.
Adjacent sequences: A115436 A115437 A115438 this_sequence A115440 A115441 A115442
Sequence in context: A059213 A093102 A139030 this_sequence A094609 A049191 A013467
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KEYWORD
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base,nonn
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AUTHOR
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Giovanni Resta (g.resta(AT)iit.cnr.it), Jan 24 2006
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