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Solutions of the equation (4*n+9)'=1, where n' is the arithmetic derivative of n. - Paolo P. Lava, Jan 03 2013

Table of n, a(n) for n=1..62.

a(n) = A005098(n+1)-2. - R. J. Mathar, Sep 23 2009

If n=98 then 4*n + 9 = 401 (prime).

Cf. A005098, A095278, A089986.

Cf. A153238, A144562.

Sequence in context: A039580 A189296 A051279 * A138671 A032724 A153308

Adjacent sequences: A111196 A111197 A111198 * A111200 A111201 A111202

nonn

Parthasarathy Nambi, Oct 24 2005

More terms from R. J. Mathar, Sep 23 2009

approved