A361639 For n > 1, A359804(n) is a multiple of A361503(n-1); a(n) = A359804(n) / A361503(n-1).

1, 1, 1, 2, 2, 2, 1, 3, 4, 3, 2, 1, 4, 4, 3, 2, 5, 6, 4, 6, 3, 5, 8, 8, 8, 6, 4, 9, 7, 13, 9, 10, 8, 12, 11, 9, 16, 12, 10, 6, 1, 13, 17, 13, 15, 19, 11, 16, 16, 12, 8, 17, 17, 23, 18, 13, 9, 26, 19, 18, 14, 20, 19, 15, 29, 10, 23, 16, 23, 24, 17, 24, 11, 18

Offset

2,4

Links

Michael De Vlieger, Table of n, a(n) for n = 2..16384

Rémy Sigrist, C program

Michael De Vlieger, Log log scatterplot of a(n), n = 2..2^20, showing 1s in red. Index on x-axis is n-1.

Example

a(10) = A359804(10) / A361503(9) = 8 / 2 = 4.

Mathematica

nn = 120; c[_] = False; q[_] = 1;
i = 1; j = 2; c[1] = c[2] = True; u = 3;
{1}~Join~Reap[Do[
     (m = q[#]; While[c[m #], m++]; k = m #; q[#] = m) &[(p = 2;
       While[Divisible[i j, p], p = NextPrime[p]]; p)]; Sow[m];
     Set[{c[k], i, j}, {True, j, k}];
If[k == u, While[c[u], u++]], {n, 3, nn}] ][[-1, -1]] (* Michael De Vlieger, Mar 19 2023 *)

Prog

(C) See Links section.

Crossrefs

Cf. A359804, A361503.

Sequence in context: A017125 A063276 A352682 * A055253 A103626 A238224

Adjacent sequences: A361636 A361637 A361638 * A361640 A361641 A361642

Keyword

nonn

Author

Rémy Sigrist, Mar 19 2023

Status

approved