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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
1, 2, 4, 10, 21, 236, 470, 29736, 60343, 199550, 476302, 4288159410, 8582063896, 3325768085554, 6660540885640, 13325577492746, 34102614679799, 5388161956623254232, 10777089239865231074, 10405445064118373530596 (list; graph; refs; listen; history; text; internal format)
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 * A036954 A109679 A023036

Adjacent sequences:  A179113 A179114 A179115 * A179117 A179118 A179119

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 10 2010

STATUS

approved

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Last modified August 22 00:43 EDT 2019. Contains 326169 sequences. (Running on oeis4.)