A305183 Least k such that A048272(k) = -n.

2, 4, 8, 16, 24, 64, 48, 256, 96, 144, 192, 4096, 240, 16384, 768, 576, 480, 262144, 720, 1048576, 960, 2304, 12288, 16777216, 1440, 5184, 49152, 3600, 3840, 1073741824, 2880, 4294967296, 3360, 36864, 786432, 20736, 5040, 274877906944, 3145728, 147456, 6720, 4398046511104, 11520, 17592186044416

Offset: 0

Author

Seiichi Manyama, May 26 2018

Keywords

• nonn

Comments

All terms are even.

Crossrefs

Cf. A005179, A048272, A187941.

Cf. A038547 (similar but with n instead of -n).

Programs

PARI

a048272(n) = sumdiv(n, d, if (d%2, 1, -1));
a(n) = {my(k=1); while (a048272(k) != -n, k++); k;} \\ Michel Marcus, May 27 2018

Formula

a(n) = 2 * A187941(n).

a(n) = 4 * A005179(n) for n > 0.