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A139634
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a(n)=10*2^(n-1)-9.
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9
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1, 11, 31, 71, 151, 311, 631, 1271, 2551, 5111, 10231, 20471, 40951, 81911, 163831, 327671, 655351, 1310711, 2621431, 5242871, 10485751, 20971511, 41943031, 83886071, 167772151, 335544311, 671088631, 1342177271, 2684354551
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Binomial transform of [1, 10, 10, 10,...].
The binomial transform of [1, c, c, c,...] has the terms a(n)=1-c+c*2^(n-1) if the offset 1 is chosen. The o.g.f. of the a(n) is x{1+(c-2)x}/{(2x-1)(x-1)}. This applies to A139634 with c=10, to A139635 with c=11, to A139697 with c=12, to A139698 with c=25 and to A099003, A139700, A139701 accordingly. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 11 2008
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FORMULA
| A007318 * [1, 10, 10, 10,...].
a(n)=2*a(n-1)+9 (with a(1)=1) [From Vincenzo Librandi, Nov 24 2010]
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EXAMPLE
| a(4) = 71 = (1, 3, 3, 1) dot (1, 10, 10, 10) = (1 + 30 + 30 + 10).
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MATHEMATICA
| a=1; lst={a}; k=10; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 17 2008]
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CROSSREFS
| Sequence in context: A085715 A040973 A141884 * A173803 A124704 A089346
Adjacent sequences: A139631 A139632 A139633 * A139635 A139636 A139637
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KEYWORD
| nonn
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AUTHOR
| Gary W. Adamson (qntmpkt(AT)yahoo.com), Apr 29 2008
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EXTENSIONS
| More terms and Mathematica program from Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 17 2008
Simpler definition from Jon Schoenfield, Jun 23 2010
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