A247034 Smallest integer x such that the number of integers y sigma(x)/x is exactly n.

1, 3, 10, 5, 9, 7, 15, 32, 132, 11, 21, 13, 44, 70, 52, 17, 25, 19, 38, 33, 198, 23, 35, 46, 39, 76, 234, 29, 220, 31, 224, 62, 51, 136, 260, 37, 57, 55, 74, 41, 1170, 43, 196, 82, 69, 47, 10440, 154, 222, 94, 520, 53, 744, 148, 77, 190, 87, 59, 182, 61, 93

Offset: 0

Author

Michel Marcus, Sep 10 2014

Keywords

• nonn

Comments

Conjecture: a(n) exists for all n.

Links

• Amiram Eldar, Table of n, a(n) for n = 0..421

Crossrefs

Cf. A000203 (sigma), A004394 (superabundant), A017665 and A017666 (sigma(n)/n).

Cf. A247015.

Programs

PARI

lista(nn) = {v = vector(nn, n, sigma(n)/n); vmore = vector(nn+1); for (n=1, nn, nb = sum(i=1, n, v[i] > v[n]); if (vmore[nb+1] == 0, vmore[nb+1] = n);); for (i=1, #vmore, if (!vmore[i], break, print1(vmore[i], ", ")));}