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A133457 Irregular triangle read by rows: row n gives exponents in expression for n as a sum of powers of 2. 32
0, 1, 0, 1, 2, 0, 2, 1, 2, 0, 1, 2, 3, 0, 3, 1, 3, 0, 1, 3, 2, 3, 0, 2, 3, 1, 2, 3, 0, 1, 2, 3, 4, 0, 4, 1, 4, 0, 1, 4, 2, 4, 0, 2, 4, 1, 2, 4, 0, 1, 2, 4, 3, 4, 0, 3, 4, 1, 3, 4, 0, 1, 3, 4, 2, 3, 4, 0, 2, 3, 4, 1, 2, 3, 4, 0, 1, 2, 3, 4, 5, 0, 5, 1, 5, 0, 1, 5, 2, 5, 0, 2, 5, 1, 2, 5, 0, 1, 2, 5, 3, 5, 0, 3, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,5
COMMENTS
This sequence contains every increasing finite sequence. For example, the finite sequence {0,2,3,5} arises from n = 45.
Essentially A030308(n,k)*k, then entries removed where A030308(n,k)=0. - R. J. Mathar, Nov 30 2007
In the corresponding irregular triangle {a(n)+1}, the m-th row gives all positive integer roots m_i of polynomial {m,k}. - see link [Shevelev]; see also A264613. - Vladimir Shevelev, Dec 13 2015
LINKS
Vladimir Shevelev, The number of permutations with prescribed up-down structure as a function of two variables, INTEGERS, 12 (2012), #A1. (See Section 3, Theorem 21 and Section 8, Theorem 50)
FORMULA
a(n) = A048793(n) - 1.
EXAMPLE
1 = 2^0.
2 = 2^1.
3 = 2^0 + 2^1.
4 = 2^2.
5 = 2^0 + 2^2.
etc. and reading the exponents gives the rows of the triangle.
MAPLE
A133457 := proc(n) local a, bdigs, i ; a := [] ; bdigs := convert(n, base, 2) ; for i from 1 to nops(bdigs) do if op(i, bdigs) <> 0 then a := [op(a), i-1] ; fi ; od: a ; end: seq(op(A133457(n)), n=1..80) ; # R. J. Mathar, Nov 30 2007
MATHEMATICA
Array[Join @@ Position[#, 1] - 1 &@ Reverse@ IntegerDigits[#, 2] &, 41] // Flatten (* Michael De Vlieger, Oct 08 2017 *)
PROG
(Haskell)
a133457 n k = a133457_tabf !! (n-1) !! n
a133457_row n = a133457_tabf !! (n-1)
a133457_tabf = map (fst . unzip . filter ((> 0) . snd) . zip [0..]) $
tail a030308_tabf
-- Reinhard Zumkeller, Oct 28 2013, Feb 06 2013
CROSSREFS
Cf. A073642 (row sums), A272011 (rows reversed).
Sequence in context: A227696 A033687 A263452 * A324120 A218857 A260803
KEYWORD
base,tabf,easy,nonn,look
AUTHOR
Masahiko Shin, Nov 27 2007
EXTENSIONS
More terms from R. J. Mathar, Nov 30 2007
STATUS
approved

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Last modified March 28 16:34 EDT 2024. Contains 371254 sequences. (Running on oeis4.)