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: [1]
Row 4: []
Row 5: [2]
Row 6: [3, 1]
Row 7: []
Row 8: [4]
Row 9: [5, 2]
MATHEMATICA
nn = 35; t = Transpose@ Table[(n^2 - n)/2 + Accumulate@ Range[n - 1, n + 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)
a273824 n = genericIndex a273824_list (n - 1)
a273824_list = concatMap a273824_row [1..]
a273824_tabf = map a273824_row [1..]
a273824_row n
| a_i == 0 = []
| otherwise = a_i : a273824_row a_i where
a_i = a271439 (n - 1)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Peter Kagey, Jun 08 2016
STATUS
approved