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 A023688 Numbers with exactly 6 ones in binary expansion. 19
 63, 95, 111, 119, 123, 125, 126, 159, 175, 183, 187, 189, 190, 207, 215, 219, 221, 222, 231, 235, 237, 238, 243, 245, 246, 249, 250, 252, 287, 303, 311, 315, 317, 318, 335, 343, 347, 349, 350, 359, 363, 365, 366, 371, 373 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sequence appears to include all numbers m such that 8^5 is the highest power of 2 dividing A005148(m). General conjecture: numbers k such that 8^j is the highest power of 2 dividing A005148(k) is the same sequence as numbers having exactly (j+1) 1's in their binary representation. - Benoit Cloitre, Jun 22 2002 LINKS Ivan Neretin, Table of n, a(n) for n = 1..10000 Robert Baillie, Summing the curious series of Kempner and Irwin, arXiv:0806.4410 [math.CA], 2008-2015. See p. 18 for Mathematica code irwinSums.m. FORMULA a(n+1) = A057168(a(n)). - M. F. Hasler, Aug 27 2014 Sum_{n>=1} 1/a(n) = 1.387753111935705074750004158584017188750706394077047633137401652680870607884... (calculated using Baillie's irwinSums.m, see Links). - Amiram Eldar, Feb 14 2022 MATHEMATICA Select[ Range[ 63, 380 ], (Count[ IntegerDigits[ #, 2 ], 1 ]==6)& ] PROG (PARI) is_A023688(n)=hammingweight(n)==6 \\ M. F. Hasler, Aug 27 2014 (PARI) print1(t=2^6-1); for(i=2, 50, print1(", "t=A057168(t))) \\ M. F. Hasler, Aug 27 2014 CROSSREFS Cf. A000079, A018900, A014311, A014312, A014313, A023689, A023690, A023691 (Hamming weight = 1..9). Cf. A005148, A057168. Sequence in context: A343003 A253021 A039480 * A118157 A257897 A261108 Adjacent sequences: A023685 A023686 A023687 * A023689 A023690 A023691 KEYWORD nonn,base,easy AUTHOR Olivier Gérard STATUS approved

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Last modified September 19 01:02 EDT 2024. Contains 376002 sequences. (Running on oeis4.)