A307309 Self-composition of the Dedekind psi function (A001615).

1, 6, 26, 99, 348, 1194, 4000, 13326, 44058, 144066, 462504, 1459194, 4545588, 14068554, 43450848, 134213808, 414692130, 1280610858, 3948172380, 12142365042, 37235047770, 113844652986, 347103133068, 1055610536520, 3202944247674, 9697395164616, 29298206343284

Offset

1,2

Links

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

Eric Weisstein's World of Mathematics, Dedekind Function

Formula

G.f.: g(g(x)), where g(x) = Sum_{k>=1} mu(k)^2*x^k/(1 - x^k)^2 is the g.f. of A001615.

Mathematica

g[x_] := g[x] = Sum[MoebiusMu[k]^2 x^k/(1 - x^k)^2, {k, 1, 27}]; a[n_] := a[n] = SeriesCoefficient[g[g[x]], {x, 0, n}]; Table[a[n], {n, 27}]

Crossrefs

Cf. A001615, A008683, A307308.

Sequence in context: A320816 A396639 A239179 * A186314 A234267 A055420

Adjacent sequences: A307306 A307307 A307308 * A307310 A307311 A307312

Keyword

nonn

Author

Ilya Gutkovskiy, Apr 02 2019

Status

approved