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A031448
Numbers whose base-2 representation has one fewer 0's than 1's.
13
1, 5, 6, 19, 21, 22, 25, 26, 28, 71, 75, 77, 78, 83, 85, 86, 89, 90, 92, 99, 101, 102, 105, 106, 108, 113, 114, 116, 120, 271, 279, 283, 285, 286, 295, 299, 301, 302, 307, 309, 310, 313, 314, 316, 327, 331, 333, 334, 339, 341, 342
OFFSET
1,2
COMMENTS
A037861(a(n)) = -1. - Reinhard Zumkeller, Mar 31 2015
The viabin numbers of the integer partitions in which the number of parts is equal to the largest part (for the definition of viabin number see comment in A290253). For example, 99 is in the sequence because it is the viabin number of the integer partition [4,2,2,2]. - Emeric Deutsch, Aug 29 2017
EXAMPLE
99 is in the sequence because its binary form is 1100011. - Emeric Deutsch, Aug 29 2017
MAPLE
vitopart := proc (n) local L, i, j, N, p, t: N := 2*n; L := ListTools:-Reverse(convert(N, base, 2)): j := 0: for i to nops(L) do if L[i] = 0 then j := j+1: p[j] := numboccur(L[1 .. i], 1) end if end do: sort([seq(p[t], t = 1 .. j)], `>=`) end proc: A := {}; for m to 500 do if nops(vitopart(m)) = max(vitopart(m)) then A := `union`(A, {m}) else end if end do: A; # program is based on my comment; the command vitopart(n) yields the integer partition having viabin number n. - Emeric Deutsch, Aug 29 2017
MATHEMATICA
Select[Range[400], DigitCount[#, 2, 1]==DigitCount[#, 2, 0]+1&] (* Harvey P. Dale, May 24 2019 *)
PROG
(Haskell)
a031448 n = a031448_list !! (n-1)
a031448_list = filter ((== -1) . a037861) [1..]
-- Reinhard Zumkeller, Mar 31 2015
CROSSREFS
Cf. A007088, A023416, A000120, A031444, subsequence of A089648.
Sequence in context: A063445 A257331 A240400 * A290254 A163772 A056509
KEYWORD
nonn,base
STATUS
approved