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Search: id:A044631
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| A044631 |
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Numbers n such that string 7,7 occurs in the base 8 representation of n but not of n+1. |
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+0
2
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| 63, 127, 191, 255, 319, 383, 447, 511, 575, 639, 703, 767, 831, 895, 959, 1023, 1087, 1151, 1215, 1279, 1343, 1407, 1471, 1535, 1599, 1663, 1727, 1791, 1855, 1919, 1983, 2047, 2111, 2175, 2239, 2303, 2367, 2431, 2495, 2559
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OFFSET
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1,1
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COMMENT
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If A=[A158067] 64*n.^2-2*n (n>0, 62, 252, 570,.,. ,.,); Y=[A010731] 8 (8,8,8,.,..,); X=[A044631] 64*n-1 (n>0, 63, 127, 191, ,. .,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 63^2-62*8^2=1; 127^2-252*8^2=1; 191^2-570*8^2=1. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 12 2009]
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LINKS
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Tanya Khovanova, Non Recursions
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FORMULA
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a(n)=64*n-1 (n>0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 12 2009]
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EXAMPLE
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For n=1, a(1)=63; n=2, a(2)=127; n=3, a(3)=191 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 12 2009]
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CROSSREFS
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Cf. A158067, A010731 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 12 2009]
Sequence in context: A043450 A031491 A044250 this_sequence A045136 A031895 A044314
Adjacent sequences: A044628 A044629 A044630 this_sequence A044632 A044633 A044634
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KEYWORD
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nonn,base
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu)
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