A361504 - OEIS

A361504

Index of n in A359804, or -1 if n never appears there.

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

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OFFSET

1,2

COMMENTS

Conjectured to be a permutation of the natural numbers.

LINKS

Table of n, a(n) for n=1..46.

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

Cf. A359804, A361502.

Sequence in context: A073884 A209293 A328021 * A377157 A097290 A279344

Adjacent sequences: A361501 A361502 A361503 * A361505 A361506 A361507

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Mar 18 2023

STATUS

approved