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A084468 Odd numbers with exactly 3 ones in binary expansion. 8
7, 11, 13, 19, 21, 25, 35, 37, 41, 49, 67, 69, 73, 81, 97, 131, 133, 137, 145, 161, 193, 259, 261, 265, 273, 289, 321, 385, 515, 517, 521, 529, 545, 577, 641, 769, 1027, 1029, 1033, 1041, 1057, 1089, 1153, 1281, 1537, 2051, 2053, 2057, 2065, 2081, 2113, 2177 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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) = 2*A018900(n) + 1 = A005408(A018900(n)).
Sum_{n>=1} 1/a(n) = 0.714295772926319061998427422200268976390844375453066534198594764887682975019... (calculated using Baillie's irwinSums.m, see Links). - Amiram Eldar, Feb 14 2022
MATHEMATICA
Flatten[Table[2^m + 2^n + 1, {m, 2, 11}, {n, m - 1}]] (* Alonso del Arte, Jul 08 2011 *)
PROG
(PARI) for(m=2, 9, for(n=1, m-1, print1(2^m+2^n+1", "))) \\ Charles R Greathouse IV, Oct 04 2011
CROSSREFS
Intersection of A005408 and A014311.
A084470(n) gives the position of a(n) in A084467(n).
Cf. A018900.
Sequence in context: A064149 A046289 A092246 * A292315 A274915 A336381
KEYWORD
nonn,base,easy
AUTHOR
Antti Karttunen, Jun 02 2003
STATUS
approved

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Last modified March 28 12:26 EDT 2024. Contains 371254 sequences. (Running on oeis4.)