The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A030130 Binary expansion contains a single 0. 12
 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; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS From Reinhard Zumkeller, 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) Zero and numbers of form 2^m-2^k-1, 2 <= m, 0 <= k <= m-2. - Zak Seidov, Aug 06 2010 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 FORMULA 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. - Ulrich Schimke (ulrschimke(AT)aol.com) a(n+1) = A140977(a(n)) for any n > 1. - Rémy Sigrist, Feb 06 2020 Sum_{n>=2} 1/a(n) = A160502. - Amiram Eldar, Oct 06 2020 EXAMPLE 23 is OK because it is '10111' in base 2. MATHEMATICA Sort[Flatten[{{0}, Table[2^n - 2^m - 1, {n, 2, 50}, {m, 0, n - 2}]}]] (* Zak Seidov, Aug 06 2010 *) PROG (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); } (Haskell) a030130 n = a030130_list !! (n-1) a030130_list = filter ((== 1) . a023416) [0..] -- Reinhard Zumkeller, Mar 31 2015, Dec 07 2012 (PARI) print1("0, "); for(k=1, 2039, my(v=digits(k, 2)); if(vecsum(v)==#v-1, print1(k, ", "))) \\ Hugo Pfoertner, Feb 06 2020 (MAGMA) [0] cat [k:k in [0..2050]| Multiplicity(Intseq(k, 2), 0) eq 1]; // Marius A. Burtea, Feb 06 2020 CROSSREFS Cf. A000918, A023416, A036563, A055010, A086224, A140977, A160502, A164874. Sequence in context: A329569 A140144 A328893 * A164874 A337498 A045845 Adjacent sequences:  A030127 A030128 A030129 * A030131 A030132 A030133 KEYWORD nonn,base,easy,look AUTHOR Toby Donaldson (tjdonald(AT)uwaterloo.ca) EXTENSIONS More terms from Erich Friedman Offset fixed by Reinhard Zumkeller, Aug 24 2009 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 18 20:45 EDT 2021. Contains 345121 sequences. (Running on oeis4.)