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A273823 Table read by rows: the n-th row is the list of numbers to the left of n in the natural numbers read by antidiagonals. 5
1, 2, 1, 3, 4, 2, 1, 5, 3, 6, 7, 4, 2, 1, 8, 5, 3, 9, 6, 10, 11, 7, 4, 2, 1, 12, 8, 5, 3, 13, 9, 6, 14, 10, 15, 16, 11, 7, 4, 2, 1, 17, 12, 8, 5, 3, 18, 13, 9, 6, 19, 14, 10, 20, 15, 21, 22, 16, 11, 7, 4, 2, 1, 23, 17, 12, 8, 5, 3, 24, 18, 13, 9, 6, 25, 19, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Peter Kagey, Table of n, a(n) for n = 1..10000

EXAMPLE

A000027 read by antidiagonals is:

1 2 4 7

3 5 8

6 9

...

Thus:

Row 1: []

Row 2: [1]

Row 3: []

Row 4: [2, 1]

Row 5: [3]

Row 6: []

Row 7: [4, 2, 1]

Row 8: [5, 3]

Row 9: [6]

MATHEMATICA

nn = 32; t = Table[(n^2 - n)/2 + Accumulate@ Range[n - 1, Ceiling[(Sqrt[9 + 8 nn] - 3)/2]] + 1, {n, Ceiling[(Sqrt[9 + 8 nn] - 3)/2] + 1}]; Table[Reverse@ Take[t[[#1]], #2 - 1] & @@ Flatten@ Position[t, n], {n, nn}] // Flatten (* Michael De Vlieger, Jun 10 2016 *)

PROG

(Haskell)

a273823 n = genericIndex a273823_list (n - 1)

a273823_list = concatMap a273823_row [1..]

a273823_tabf = map a273823_row [1..]

a273823_row n

  | a_i == 0  = []

  | otherwise = a_i : a273823_row a_i where

    a_i = a271439 n

CROSSREFS

Cf. A000027, A025581 (row length), A269526, A271439, A273824, A273825, A274079, A274080.

Sequence in context: A341231 A334081 A125158 * A112384 A248514 A123390

Adjacent sequences:  A273820 A273821 A273822 * A273824 A273825 A273826

KEYWORD

nonn,tabf,look

AUTHOR

Peter Kagey, Jun 08 2016

STATUS

approved

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Last modified March 6 03:35 EST 2021. Contains 341841 sequences. (Running on oeis4.)