A273825 Table read by rows: the n-th row is the list of numbers diagonally up and to the left of n in the natural numbers read by antidiagonals.

1, 2, 3, 4, 5, 1, 6, 7, 8, 2, 9, 3, 10, 11, 12, 4, 13, 5, 1, 14, 6, 15, 16, 17, 7, 18, 8, 2, 19, 9, 3, 20, 10, 21, 22, 23, 11, 24, 12, 4, 25, 13, 5, 1, 26, 14, 6, 27, 15, 28, 29, 30, 16, 31, 17, 7, 32, 18, 8, 2, 33, 19, 9, 3, 34, 20, 10, 35, 21, 36, 37, 38, 22

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: []
Row 3: []
Row 4: []
Row 5: [1]
Row 6: []
Row 7: []
Row 8: [2]
Row 9: [3]

Mathematica

nn = 58; 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[Rest@ Map[t[[#1, #2]] & @@ # &, Most@ NestWhileList[# - 1 &, #, ! MemberQ[#, 0] &]] &@ First@ Position[t, n], {n, nn}] // Flatten (* Michael De Vlieger, Jun 29 2016 *)

Prog

(Haskell)
a273825 n = genericIndex a273825_list (n - 1)
a273825_list = concatMap a273825_row [1..]
a273825_tabf = map a273825_row [1..]
a273825_row n
  | a_i == 0  = []
  | otherwise = a_i : a273825_row a_i where
    a_i = a271439 $ a271439 (n - 1)

Crossrefs

Cf. A000027, A269526, A271439, A273823, A273824, A274079, A274080.

Sequence in context: A071514 A243731 A334945 * A082299 A081806 A059806

Adjacent sequences: A273822 A273823 A273824 * A273826 A273827 A273828

Keyword

nonn,tabf

Author

Peter Kagey, Jun 08 2016

Status

approved