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A230092 Numbers of the form k + wt(k) for exactly three distinct k, where wt(k) = A000120(k) is the binary weight of k. 12
129, 134, 386, 391, 515, 518, 642, 647, 899, 904, 1028, 1030, 1154, 1159, 1411, 1416, 1540, 1543, 1667, 1672, 1924, 1929, 2178, 2183, 2435, 2440, 2564, 2567, 2691, 2696, 2948, 2953, 3077, 3079, 3203, 3208, 3460, 3465, 3589, 3592, 3716, 3721, 3973, 3978, 4226 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The positions of entries equal to 3 in A228085, or numbers that appear exactly thrice in A092391.
Numbers that can be expressed as the sum of distinct terms of the form 2^n+1, n=0,1,... in exactly three ways.
LINKS
Reinhard Zumkeller and Donovan Johnson, Table of n, a(n) for n = 1..10000 (first 1000 terms from Reinhard Zumkeller)
MAPLE
For Maple code see A230091.
MATHEMATICA
nt = 1000; (* number of terms to produce *)
S[kmax_] := S[kmax] = Table[k + Total[IntegerDigits[k, 2]], {k, 0, kmax}] // Tally // Select[#, #[[2]] == 3&][[All, 1]]& // PadRight[#, nt]&;
S[nt];
S[kmax = 2 nt];
While[S[kmax] =!= S[kmax/2], kmax *= 2];
S[kmax] (* Jean-François Alcover, Mar 04 2023 *)
PROG
(Haskell)
a230092 n = a230092_list !! (n-1)
a230092_list = filter ((== 3) . a228085) [1..]
-- Reinhard Zumkeller, Oct 13 2013
CROSSREFS
Cf. A227915.
Sequence in context: A298720 A025332 A025324 * A060878 A127337 A185347
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Oct 10 2013
STATUS
approved

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Last modified February 26 11:46 EST 2024. Contains 370352 sequences. (Running on oeis4.)