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

Offset: 1

Author

N. J. A. Sloane, Mar 18 2023

Keywords

• nonn
• more

Comments

Conjectured to be a permutation of the natural numbers.

Crossrefs

Cf. A359804, A361502.

Programs

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 *)