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Search: id:A023001
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| 0, 1, 9, 73, 585, 4681, 37449, 299593, 2396745, 19173961, 153391689, 1227133513, 9817068105, 78536544841, 628292358729, 5026338869833, 40210710958665, 321685687669321, 2573485501354569, 20587884010836553, 164703072086692425
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Gives the (zero-based) positions of odd terms in A007556 (Mod[A007556[A0023001(n)],2]=1). - Farideh_Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jun 13 2003
a(n) = A033138(3n-2). - Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), May 31 2005
{1, 9, 73, 585, 4681, ...} is the binomial transform of A003950 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jul 22 2005
Except for the first term, a(n)=8*a(n-1)+1 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 29 2009]
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LINKS
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Index entries for sequences related to linear recurrences with constant coefficients
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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FORMULA
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Also sum of cubes of divisors of 2^(n-1): a(n)=A001158[A000079(n-1)] - Labos E. (labos(AT)ana.sote.hu), Apr 10 2003 and Farideh_Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jun 13 2003
a(0)=0, a(n)=8*a(n-1)+1 for n>0 . G.f.:x/((1-8x)*(1-x)) - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 12 2006
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EXAMPLE
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Octal.............decimal (comment from Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 14 2007):
0....................0
1....................1
11...................9
111.................73
1111...............585
11111.............4681
111111...........37449
1111111.........299593
11111111.......2396745
111111111.....19173961
1111111111...153391689
etc. ...............etc.
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MAPLE
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a:=n->sum(8^(n-j), j=1..n): seq(a(n), n=0..20); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 04 2007
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MATHEMATICA
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Table[(8^n-1)/7, {n, 0, m}]
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PROGRAM
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(Other) sage: [lucas_number1(n, 9, 8) for n in xrange(0, 21)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 23 2009]
(Other) sage: [gaussian_binomial(n, 1, 8) for n in xrange(0, 21)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 28 2009]
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CROSSREFS
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Cf. A007556.
Sequence in context: A126641 A081627 A164588 this_sequence A015454 A121246 A086226
Adjacent sequences: A022998 A022999 A023000 this_sequence A023002 A023003 A023004
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KEYWORD
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easy,nonn
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AUTHOR
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David W. Wilson (davidwwilson(AT)comcast.net)
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