A179116 G.f.: A(x) = exp( Sum_{n>=1} 2*A179117(n)*x^n/n ), where A179117(n) = Sum_{d|n} phi(d^phi(d)).

1, 2, 4, 10, 21, 236, 470, 29736, 60343, 199550, 476302, 4288159410, 8582063896, 3325768085554, 6660540885640, 13325577492746, 34102614679799, 5388161956623254232, 10777089239865231074, 10405445064118373530596

Offset

0,2

Comments

phi(n) = A000010(n) is the Euler totient function of n.

Links

Table of n, a(n) for n=0..19.

Example

G.f.: A(x) = 1 + 2*x + 4*x^2 + 10*x^3 + 21*x^4 + 236*x^5 + 470*x^6 +...
log(A(x)) = 2*x + 4*x^2/2 + 14*x^3/3 + 20*x^4/4 + 1002*x^5/5 + 40*x^6/6 +...

Prog

(PARI) {a(n)=polcoeff(exp(sum(m=1, n, sumdiv(m, d, 2*eulerphi(d^eulerphi(d)))*x^m/m)+x*O(x^n)), n)}

Crossrefs

Cf. A179117, A000010 (phi).

Sequence in context: A123445 A104431 A130666 * A358357 A036954 A109679

Adjacent sequences: A179113 A179114 A179115 * A179117 A179118 A179119

Keyword

nonn

Author

Paul D. Hanna, Jul 10 2010

Status

approved