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Search: id:A010860
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| 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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A141722(n+1)-4*A141722(n). A141722=10*A000975(2n)+A000975(2n+1)= 1, 25 121 . [From Paul Curtz (bpcrtz(AT)free.fr), Sep 17 2008]
If A=[A157737] 441*n.^2-2*n (n>0, 439, 1760, 3963,.,); Y=[A010860] 21 (21, 21, 21 ,.,); X=[A158319] 441*n-1 (n>0, 440, 881, 1322, .,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 440^2-439*21^2=1; 881^2-1760*21^2=1; 1322^2-3963*21^2=1. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 16 2009]
If A=[A158321] 441*n.^2+2*n (n>0, 443, 1768, 3975,.,); Y=[A010860] 21 (21, 21, 21 ,.,); X=[A158322] 441*n+1 (n>0, 442, 883, 1324, .,), we have, for all terms, Pell's equation X^2-A*Y^2=1. Example: 442^2-443*21^2=1; 883^2-1768*21^2=1; 1324^2-3975*21^2=1. [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 16 2009]
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LINKS
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Tanya Khovanova, Recursive Sequences
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CROSSREFS
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Cf. A157737, A158319 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 16 2009]
Cf. A158321, A158322 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Mar 16 2009]
Sequence in context: A023463 A004462 A154352 this_sequence A158772 A144415 A040421
Adjacent sequences: A010857 A010858 A010859 this_sequence A010861 A010862 A010863
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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