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A362131 a(n) = smallest missing number u in A360179(1..n). 4
2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 6, 7, 7, 7, 7, 7, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 11, 11, 11, 11, 11, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 20, 20, 20, 20, 20, 20, 20, 20, 21, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Michael De Vlieger, Labeled scatterplot of A360179(n), n = 1..300, showing a(n) in small red dots, and A360179(n) in large red when A360179(n) = a(n-1).
MATHEMATICA
nn = 120; c[_] := False; q[_] := False; h[_] := 0; f[n_] := DivisorSigma[0, n];
a[1] = j = u = w = 1;
{2}~Join~Reap[Do[
If[c[j],
k = j + f[u]; h[j]++; h[u]--,
k = f[j]; c[j] = True; h[j]++ ];
u = Min[u, j]; Set[{a[n], q[k], j}, {k, True, k}];
While[h[u] == 0, u++]; If[k == w, While[q[w], w++]];
Sow[w], {n, 2, nn}] ][[-1, -1]]
CROSSREFS
Sequence in context: A327247 A210609 A210608 * A095773 A062108 A100682
KEYWORD
nonn
AUTHOR
Michael De Vlieger, Apr 10 2023
STATUS
approved

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Last modified June 17 12:36 EDT 2024. Contains 373445 sequences. (Running on oeis4.)