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A158405
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Triangle T(n,m) = 1+2*m of odd numbers read along rows, 0<=m<n.
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19
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1, 1, 3, 1, 3, 5, 1, 3, 5, 7, 1, 3, 5, 7, 9, 1, 3, 5, 7, 9, 11, 1, 3, 5, 7, 9, 11, 13, 1, 3, 5, 7, 9, 11, 13, 15, 1, 3, 5, 7, 9, 11, 13, 15, 17, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23
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OFFSET
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1,3
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COMMENTS
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Row sums are n^2 = A000290(n).
The triangle sums, see A180662 for their definitions, link this triangle of odd numbers with seventeen different sequences, see the crossrefs. The knight sums Kn14 - Kn110 have been added. - Johannes W. Meijer, Sep 22 2010
A208057 is the eigentriangle of A158405 such that as infinite lower triangular matrices, A158405 * A208057 shifts the latter, deleting the right border of 1's. - Gary W. Adamson, Feb 22 2012
T(n,k) = A099375(n-1,n-k), 1<=k<=n. [Reinhard Zumkeller, Mar 31 2012]
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LINKS
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Seiichi Manyama, Rows n = 1..140, flattened
Daniel Erman, The Josephus Problem, Numberphile video (2016)
Boris Putievskiy, Transformations [of] Integer Sequences And Pairing Functions arXiv:1212.2732 [math.CO], 2012.
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FORMULA
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a(n)= 2*i-1, where i = n-t(t+1)/2, t = floor((-1+sqrt(8*n-7))/2). - Boris Putievskiy, Feb 03 2013
a(n)= 2*A002262(n-1) + 1. - Eric Werley, Sep 30 2015
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EXAMPLE
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The triangle contains the first n odd numbers in row n:
1;
1,3;
1,3,5;
1,3,5,7;
From Seiichi Manyama, Dec 02 2017: (Start)
| a(n) | | A000290(n)
-----------------------------------------------------------------
0| (= 0)
1| 1 = 1/3 * ( 3) (= 1)
2| 1 + 3 = 1/3 * ( 5 + 7) (= 4)
3| 1 + 3 + 5 = 1/3 * ( 7 + 9 + 11) (= 9)
4| 1 + 3 + 5 + 7 = 1/3 * ( 9 + 11 + 13 + 15) (= 16)
5| 1 + 3 + 5 + 7 + 9 = 1/3 * (11 + 13 + 15 + 17 + 19) (= 25)
(End)
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MATHEMATICA
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Table[2 Range[1, n] - 1, {n, 12}] // Flatten (* Michael De Vlieger, Oct 01 2015 *)
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PROG
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(Haskell)
a158405 n k = a158405_row n !! (k-1)
a158405_row n = a158405_tabl !! (n-1)
a158405_tabl = map reverse a099375_tabl
-- Reinhard Zumkeller, Mar 31 2012
(PARI) a(n) = 2*(n-floor((-1+sqrt(8*n-7))/2)*(floor((-1+sqrt(8*n-7))/2)+1)/2)-1;
vector(100, n, a(n)) \\ Altug Alkan, Oct 01 2015
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CROSSREFS
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Cf. A129326, A099375, A005408.
Triangle sums (see the comments): A000290 (Row1; Kn11 & Kn4 & Ca1 & Ca4 & Gi1 & Gi4); A000027 (Row2); A005563 (Kn12); A028347 (Kn13); A028560 (Kn14); A028566 (Kn15); A098603 (Kn16); A098847 (Kn17); A098848 (Kn18); A098849 (Kn19); A098850 (Kn110); A000217 (Kn21. Kn22, Kn23, Fi2, Ze2); A000384 (Kn3, Fi1, Ze3); A000212 (Ca2 & Ze4); A000567 (Ca3, Ze1); A011848 (Gi2); A001107 (Gi3). - Johannes W. Meijer, Sep 22 2010
Cf. A063656, A063657, A208057, A292610, A292611.
Sequence in context: A130465 A272120 A194437 * A113759 A294966 A258208
Adjacent sequences: A158402 A158403 A158404 * A158406 A158407 A158408
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KEYWORD
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nonn,tabl,easy
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AUTHOR
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Paul Curtz, Mar 18 2009
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EXTENSIONS
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Edited by R. J. Mathar, Oct 06 2009
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STATUS
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approved
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