A336673 Numbers k such that A063659(k) = A063659(k+1).

3, 49, 1681, 18490, 23762, 656914, 843637, 5606230, 35558770, 46297822, 59006794, 114594493, 132859642, 138852445, 157906534, 289405462, 299441785, 536671282, 813736930, 1175272581, 1276553470, 1655870629, 5086602202, 5429407657, 6549516022, 8645559934, 10373399185

Offset

1,1

Comments

Analogous to A001274 as A063659 is analogous to Euler's phi function (A000010).

Links

Table of n, a(n) for n=1..27.

E. K. Haviland, An analogue of Euler's phi-function, Duke Math. J., Vol. 11 (1944), pp. 869-872.

Example

3 is a term since A063659(3) = A063659(4) = 3.

Mathematica

f[p_, e_] := If[e == 1, p, p^e - p^(e-2)]; s[n_] := Times @@ f @@@ FactorInteger[n]; s1 = 1; seq = {}; Do[s2 = s[n]; If[s1 == s2, AppendTo[seq, n-1]]; s1 = s2, {n, 2, 10^5}]; seq

Crossrefs

Cf. A000010, A063659, A001274.

Sequence in context: A303248 A369942 A187664 * A012199 A337154 A300990

Adjacent sequences: A336670 A336671 A336672 * A336674 A336675 A336676

Keyword

nonn

Author

Amiram Eldar, Jul 29 2020

Status

approved