A189559 - OEIS

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A189559

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

2, 5, 31, 167, 151, 491, 983, 887, 311, 1151, 1559, 2111, 1031, 2711, 4391, 4271, 3671, 3191, 5351, 9551, 11471, 14759, 8951, 13751, 11831, 5591, 19991, 10391, 15791, 28031, 30071, 37511, 43151, 27191, 40031, 31391, 52631, 53231, 35591, 52391, 50951

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

It is much easier finding composite numbers having many solutions. See A189558. For odd numbers, see A189560.

REFERENCES

See A003415.

LINKS

Donovan Johnson, Table of n, a(n) for n = 0..200

FORMULA

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

CROSSREFS