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A256440
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Regular triangle where the n-th row lists the integers k between 1 and n ordered by increasing value of sigma(k)/k where sigma is the sum of divisors, A000203.
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4
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1, 1, 2, 1, 3, 2, 1, 3, 2, 4, 1, 5, 3, 2, 4, 1, 5, 3, 2, 4, 6, 1, 7, 5, 3, 2, 4, 6, 1, 7, 5, 3, 2, 4, 8, 6, 1, 7, 5, 3, 9, 2, 4, 8, 6, 1, 7, 5, 3, 9, 2, 4, 10, 8, 6, 1, 11, 7, 5, 3, 9, 2, 4, 10, 8, 6, 1, 11, 7, 5, 3, 9, 2, 4, 10, 8, 6, 12, 1, 13, 11, 7, 5, 3, 9, 2, 4, 10, 8, 6, 12
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,3
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LINKS
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Michel Marcus, Rows n = 1..100 of triangle, flattened
Michel Marcus, 100 rows
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EXAMPLE
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Triangle starts:
1;
1, 2;
1, 3, 2;
1, 3, 2, 4;
1, 5, 3, 2, 4;
1, 5, 3, 2, 4, 6;
1, 7, 5, 3, 2, 4, 6;
...
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MATHEMATICA
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f[n_] := Block[{t = Table[0, {n}], j, k}, For[j = 1, j <= n, j++, t[[j]] = {}; For[k = 1, k <= j, k++, AppendTo[t[[j]], DivisorSigma[1, k]/k]]]; Ordering /@ t]; f@ 13 // Flatten (* Michael De Vlieger, Mar 29 2015 *)
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PROG
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(PARI) lista(nn) = {for (n=1, nn, v = vector(n, k, sigma(k)/k); w = vecsort(v, , 1); for (k=1, n, print1(w[k], ", ")); print(); ); }
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CROSSREFS
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Cf. A000203, A247015, A247022.
Sequence in context: A082074 A132283 A307081 * A088370 A328719 A113787
Adjacent sequences: A256437 A256438 A256439 * A256441 A256442 A256443
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KEYWORD
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nonn,tabl
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AUTHOR
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Michel Marcus, Mar 29 2015
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STATUS
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approved
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