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Search: id:A123672
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| A123672 |
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a(1)=1; for n > 1, a(n)=(2^n-1)*a(n-1)+(-1)^n. |
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+0
1
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| 1, 4, 27, 406, 12585, 792856, 100692711, 25676641306, 13120763707365, 13422541272634396, 27475941985082608611, 112513982428913282262046, 921602030075228695008418785, 15098606058722471710322924954656
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This sequence allows us to prove that the constant C defined in A048651 is irrationnal. Indeed, for any n >1 we get |(C+1)*A005329(n)-a(n)|<1/2^n
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REFERENCES
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J. Lynch et al., Irrationnality of an infinite product, Amer. Math. Monthly 87 (1980) 408-409
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PROGRAM
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(PARI) a(n)=if(n<2, 1, (2^n-1)*a(n-1)+(-1)^n)
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CROSSREFS
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Cf. A005329, A048651.
Adjacent sequences: A123669 A123670 A123671 this_sequence A123673 A123674 A123675
Sequence in context: A119820 A058155 A104169 this_sequence A119030 A120093 A133018
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 16 2006
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