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A108019
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a(n)=(8^n-1)*4/7.
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1
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0, 4, 36, 292, 2340, 18724, 149796, 1198372, 9586980, 76695844, 613566756, 4908534052, 39268272420, 314146179364, 2513169434916, 20105355479332, 160842843834660, 1286742750677284, 10293942005418276, 82351536043346212
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Numbers n whose binary representation is 100, n times.
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FORMULA
| a(n)=8*a(n-1)+4 (with a(0)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 13 2010]
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EXAMPLE
| a(3)=292 because 292 translated in base 2 is three times 100: 100100100.
Octal...............decimal (comment from Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 14 2007):
0......................0
4......................4
44....................36
444..................292
4444................2340
44444..............18724
444444............149796
4444444..........1198372
44444444.........9586980
444444444.......76695844
4444444444.....613566756
etc. ...............etc.
a(1)=8*0+4=4; a(2)=8*4+4=36; a(3)=8*36+4=292 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 13 2010]
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MATHEMATICA
| Table[ FromDigits[ Flatten[ Table[{1, 0, 0}, {i, n}]], 2], {n, 0, 19}] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 01 2005)
s=0; lst={s}; Do[s+=2^n; AppendTo[lst, s], {n, 2, 5!, 3}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 07 2008]
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PROG
| (PARI) a(n)=if(n<0, 0, (8^n-1)*4/7) (Michael Somos)
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CROSSREFS
| Sequence in context: A098916 A180170 A059416 * A093186 A000765 A189334
Adjacent sequences: A108016 A108017 A108018 * A108020 A108021 A108022
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KEYWORD
| easy,nonn
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AUTHOR
| Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), May 31 2005
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 01 2005
simplify! [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Nov 07 2008]
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