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Search: id:A007178
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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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+0
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; listen)
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OFFSET
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1,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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.
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FORMULA
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a(n) = coefficient of z^2^n in (z+z^2+z^4+...+z^2^(n-1))^n - D. E. Knuth.
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CROSSREFS
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Cf. A002572.
Adjacent sequences: A007175 A007176 A007177 this_sequence A007179 A007180 A007181
Sequence in context: A110193 A038762 A074517 this_sequence A034172 A000670 A032036
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe, D. E. Knuth
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EXTENSIONS
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More terms from Hugo van der Sanden (hv(AT)crypt.org)
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