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 A343854 Irregular triangle read by rows: the n-th row gives the column indices of the matrix of 1..n^2 filled successively back and forth along antidiagonals. 2
 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 3, 3, 2, 3, 1, 2, 1, 1, 2, 3, 4, 3, 2, 1, 2, 3, 4, 4, 3, 4, 1, 2, 1, 1, 2, 3, 4, 3, 2, 1, 1, 2, 3, 4, 5, 5, 4, 3, 2, 3, 4, 5, 5, 4, 5, 1, 2, 1, 1, 2, 3, 4, 3, 2, 1, 1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 6, 6, 5, 4, 3, 4, 5, 6, 6, 5, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Stefano Spezia, First 30 rows of the triangle, flattened EXAMPLE The triangle begins: 1 1 2 1 2 1 2 1 1 2 3 3 2 3 1 2 1 1 2 3 4 3 2 1 2 3 4 4 3 4 ... MATHEMATICA a={}; For[n=1, n<=6, n++, For[d=1, d<=n, d++, If[EvenQ[d], i=d; For [k=1, k<=d, k++, AppendTo[a, i-k+1]], i=1; For[k=1, k<=d, k++, AppendTo[a, i+k-1]]]]; For[d=n+1, d<=2n-1, d++, If[EvenQ[d], i= n; For[k=1, k<=2n-d, k++, AppendTo[a, i-k+1]], If[OddQ[d], i=d-n+1; For[k=1, k<=2n-d, k++, AppendTo[a, i+k-1]]]]]]; a CROSSREFS Cf. A000290 (row length), A002411 (row sums), A060747 (number of antidiagonals), A078475, A319572, A343853 (row indices). Sequence in context: A104248 A358359 A249973 * A069349 A167404 A280223 Adjacent sequences: A343851 A343852 A343853 * A343855 A343856 A343857 KEYWORD nonn,look,tabf AUTHOR Stefano Spezia, May 01 2021 STATUS approved

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Last modified July 25 01:41 EDT 2024. Contains 374585 sequences. (Running on oeis4.)