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 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. 5
 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 (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: [] 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

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Last modified April 22 22:19 EDT 2021. Contains 343197 sequences. (Running on oeis4.)