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Search: id:A030130
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| A030130 |
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Binary expansion contains a single 0. |
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+0
7
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| 0, 2, 5, 6, 11, 13, 14, 23, 27, 29, 30, 47, 55, 59, 61, 62, 95, 111, 119, 123, 125, 126, 191, 223, 239, 247, 251, 253, 254, 383, 447, 479, 495, 503, 507, 509, 510, 767, 895, 959, 991, 1007, 1015, 1019, 1021, 1022, 1535, 1791, 1919, 1983, 2015, 2031, 2039
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Contribution from Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 29 2009: (Start)
A023416(a(n)) = 1;
apart from the initial term the sequence can be seen as a triangle read by rows, see A164874;
A055010 and A086224 are subsequences, see also A000918 and A036563. (End)
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LINKS
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R. Zumkeller, Table of n, a(n) for n = 1..1000 [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 29 2009]
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FORMULA
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a(n) = 2^(g(n))-1-2^(((2*g(n)-1)^2-1-8*n)/8) with g(n)=int((sqrt(8*n-7)+3)/2) for all n>0 and g(0)=1 - UlrSchimke(AT)aol.com.
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EXAMPLE
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23 is OK because it is '10111' in base 2.
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PROGRAM
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(C) long int element (long int i) { return (pow(2, g(i))-1-pow(2, (pow(2*g(i)-1, 2)-1-8*i)/8)); } long int g(long int m) {if (m==0) return(1); return ((sqrt(8*m-7)+3)/2); }
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CROSSREFS
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Sequence in context: A026344 A057812 A140144 this_sequence A164874 A045845 A002133
Adjacent sequences: A030127 A030128 A030129 this_sequence A030131 A030132 A030133
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KEYWORD
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nonn,base,easy
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AUTHOR
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Toby Donaldson (tjdonald(AT)uwaterloo.ca)
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EXTENSIONS
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More terms from Erich Friedman (erich.friedman(AT)stetson.edu).
Offset fixed by Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 24 2009
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