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 A253580 A fractal tree, read by rows: for n > 1: T(n,0) = T(n-1,0)+2, T(n,2*n) = T(n-1,0)+3, and for k=1..2*n-1: T(n,k) = T(n-1,k-1). 5
 0, 1, 0, 2, 3, 1, 0, 2, 4, 5, 3, 1, 0, 2, 4, 6, 7, 5, 3, 1, 0, 2, 4, 6, 8, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 11, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 12, 13, 11, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 12, 14, 15, 13, 11, 9, 7, 5, 3, 1, 0, 2, 4, 6, 8, 10, 12, 14, 16 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS If all pairs of consecutive terms (i,i+1) (such as (0,1), (1,2), (2,3), ...) are erased, the original sequence appears; see also A253607. T(n,n-k) + T(n,n+k) = 4*k - 1 for k = 1..n; T(n+m,k) = T(n,k) for m > 0, k = 0 .. 2*n. REFERENCES V. A. Sankar Ponnapalli and V. Y. Jayasree Pappu, Design of Octagonal Fractal Array Antenna for Side Lobe Reduction with Morse-Thue Fractal Density Tapering Technique, Preprint, 2016. LINKS Reinhard Zumkeller, Rows n = 0..100 of triangle, flattened Éric Angelini, More fractal trees - and erasures, SeqFan list, Jan 04 2015. EXAMPLE .   0:                                 0 .   1:                               1 0 2 .   2:                             3 1 0 2 4 .   3:                           5 3 1 0 2 4 6 .   4:                         7 5 3 1 0 2 4 6 8 .   5:                       9 7 5 3 1 0 2 4 6 8 10 .   6:                    11 9 7 5 3 1 0 2 4 6 8 10 12 .   7:                 13 11 9 7 5 3 1 0 2 4 6 8 10 12 14 .   8:              15 13 11 9 7 5 3 1 0 2 4 6 8 10 12 14 16 .   9:           17 15 13 11 9 7 5 3 1 0 2 4 6 8 10 12 14 16 18 .  10:        19 17 15 13 11 9 7 5 3 1 0 2 4 6 8 10 12 14 16 18 20 .  11:     21 19 17 15 13 11 9 7 5 3 1 0 2 4 6 8 10 12 14 16 18 20 22 .  12:  23 21 19 17 15 13 11 9 7 5 3 1 0 2 4 6 8 10 12 14 16 18 20 22 24 . MATHEMATICA a[n_, k_] := 2 Abs[n-k] - Boole[k

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Last modified April 23 07:51 EDT 2019. Contains 322381 sequences. (Running on oeis4.)