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Search: id:A136258
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| A136258 |
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a(n)=2a(n-1)-2a(n-2), with a(0)=1, a(1)=5. |
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+0
1
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| 1, 5, 8, 6, -4, -20, -32, -24, 16, 80, 128, 96, -64, -320, -512, -384, 256, 1280, 2048, 1536, -1024, -5120, -8192, -6144, 4096, 20480, 32768, 24576, -16384, -81920, -131072, -98304, 65536, 327680, 524288, 393216, -262144, -1310720, -2097152, -1572864, 1048576
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Sequence opposite in sign to its second differences.
Binomial transform of 1, 4, -1, -4.
A bisection gives A135520.
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FORMULA
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a(4n+1)=5*(-4)^n, a(4n+3)=6*(-4)^n. - M. F. Hasler, May 01 2008
a(n)=(1/2+2*I)*(1-I)^n+(1/2-2*I)*(1+I)^n, with n>=0 and I=sqrt(-1) - Paolo P. Lava (ppl(AT)spl.at), Jun 09 2008
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PROGRAM
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(PARI) vector(100, n, t=if(n<3, [t1=1, 5][n], -2*t1+2*t1=t)) \\ - M. F. Hasler, May 01 2008
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CROSSREFS
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Adjacent sequences: A136255 A136256 A136257 this_sequence A136259 A136260 A136261
Sequence in context: A059742 A011424 A011495 this_sequence A102519 A085117 A070371
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KEYWORD
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sign,easy
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AUTHOR
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Paul Curtz (bpcrtz(AT)free.fr), Mar 18 2008
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EXTENSIONS
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Edited and extended by M. F. Hasler (www.univ-ag.fr/~mhasler), May 01 2008
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