A189558 Least number k>0 such that x' = k has n solutions, where x' is the arithmetic derivative (A003415) of x.

2, 4, 10, 16, 24, 54, 48, 60, 84, 90, 114, 144, 150, 120, 168, 234, 216, 252, 288, 210, 354, 240, 432, 360, 330, 552, 456, 390, 462, 480, 546, 420, 510, 600, 672, 792, 756, 714, 798, 690, 720, 630, 1116, 1026, 930, 780, 870, 960, 900, 924, 1134, 1296, 840

Offset

0,1

Comments

It appears that all terms are even. See A189559 for k restricted to prime numbers and A189560 restricted to odd numbers.

References

See A003415.

Links

T. D. Noe and Donovan Johnson, Table of n, a(n) for n = 0..5000 (terms up to a(665) from T. D. Noe)

Formula

a(n) is the least k>0 such that A099302(k) = n.

Crossrefs

See A003415, A099302, A189559, A189560.

Sequence in context: A096689 A039682 A218665 * A111149 A123689 A137928

Adjacent sequences: A189555 A189556 A189557 * A189559 A189560 A189561

Keyword

nonn

Author

T. D. Noe, Apr 24 2011

Status

approved