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A138738 E.g.f. satisfies: A(x) = exp(x*exp(x^2*exp(x^3*exp(...exp(x^n*...))))). 1
1, 1, 1, 7, 25, 121, 1561, 9871, 101137, 1293265, 15765841, 226501111, 3355388521, 55348183177, 981791212585, 19611613003711, 387083895223201, 8241127257050401, 193814428658623777, 4572332597344204135, 116627907470591924281, 3142752742361513926681 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

a(n) == 1 (mod 6)  (conjecture).

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..400

EXAMPLE

E.g.f: A(x) = 1 + x + 1/2*x^2 + 7/6*x^3 + 25/24*x^4 + 121/120*x^5 +...

PROG

(PARI) {a(n)=local(A=1); for(i=0, n-1, A=exp(x^(n-i)*A+x*O(x^n))); n!*polcoeff(A, n)}

for(n=0, 30, print1(a(n), ", "))

CROSSREFS

Cf. A138292.

Sequence in context: A216688 A141626 A138292 * A057573 A082651 A241714

Adjacent sequences:  A138735 A138736 A138737 * A138739 A138740 A138741

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 27 2008

STATUS

approved

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Last modified May 31 07:22 EDT 2020. Contains 334747 sequences. (Running on oeis4.)