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A361504 Index of n in A359804, or -1 if n never appears there. 4
1, 2, 3, 5, 4, 6, 8, 10, 9, 7, 13, 14, 42, 12, 11, 24, 347, 19, 3466, 15, 16, 17, 49012, 25, 18, 31, 32, 20, 528231, 21, 717126, 38, 22, 44, 23, 35, 63056215, 47, 45, 26, 1375559400, 27, 7038527851, 28, 29, 55 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Conjectured to be a permutation of the natural numbers.
LINKS
MATHEMATICA
nn = 2^20; c[_] = 0; q[_] = 1;
Array[Set[{a[#], c[#]}, {#, #}] &, 2];
Set[{i, j}, {a[1], a[2]}]; u = 3;
Monitor[Do[
(k = q[#]; While[c[k #] > 0, k++]; k *= #;
While[c[# q[#]] > 0, q[#]++]) &[(p = 2;
While[Divisible[i j, p], p = NextPrime[p]]; p)]; Sow[p];
Set[{a[n], c[k], i, j}, {k, n, j, k}];
If[k == u, While[c[u] > 0, u++]], {n, 3, nn}], n];
TakeWhile[Array[c, 120], # > 0 &] (* Michael De Vlieger, Mar 18 2023 *)
CROSSREFS
Sequence in context: A073884 A209293 A328021 * A097290 A279344 A316669
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Mar 18 2023
STATUS
approved

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Last modified June 2 11:44 EDT 2023. Contains 363097 sequences. (Running on oeis4.)