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A007178
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Number of ways to write 1 as ordered sum of n powers of 1/2, allowing repeats.
(Formerly M2951)
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9
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1, 1, 3, 13, 75, 525, 4347, 41245, 441675, 5259885, 68958747, 986533053, 15292855019, 255321427725, 4567457001915, 87156877087069, 1767115200924299, 37936303950503853, 859663073472084315, 20505904049009202685, 513593410566661282347
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| D. E. Knuth, personal communication.
S. Lehr, J. Shallit and J. Tromp, On the vector space of the automatic reals, Theoret. Comput. Sci. 163 (1996), no. 1-2, 193-210.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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FORMULA
| a(n) = coefficient of z^(2^n) in (z+z^2+z^4+...+z^(2^n))^n - D. E. Knuth.
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CROSSREFS
| Cf. A002572.
Sequence in context: A110193 A038762 A074517 * A173990 A034172 A000670
Adjacent sequences: A007175 A007176 A007177 * A007179 A007180 A007181
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KEYWORD
| nonn,easy,nice
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe, D. E. Knuth
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EXTENSIONS
| More terms from Hugo van der Sanden (hv(AT)crypt.org)
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