0,3

G.f.: A(x)=1+x/B(x)^3, B(x)=1+x/C(x)^6, C(x)=1+x/D(x)^9, D(x)=1+x/E(x)^12, ...

where A(x),B(x),C(x),... are the g.f. of the sequences given below.

A=[1,1,-3,24,-307,5367,-118836,3185098,-100249284,...];

B=[1,1,-6,75,-1352,31167,-867294,28172631,-1044977994,...];

C=[1,1,-9,153,-3567,102591,-3461832,133195605,-5737614804,...];

D=[1,1,-12,258,-7384,254955,-10139508,452535442,-22298633472,...];

E=[1,1,-15,390,-13235,533700,-24472908,1245207030,-69239330640,...];

F=[1,1,-18,549,-21552,994392,-51685074,2955896076,-183324843810,...]; ...

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(j=0, n-1, A=1+x*A^(-3*(n-j))); polcoeff(A, n)}

Cf. A121587, A138213, A138210, A138208.

Sequence in context: A128572 A052592 A059381 this_sequence A075142 A138428 A047056

Adjacent sequences: A138206 A138207 A138208 this_sequence A138210 A138211 A138212

sign

Paul D. Hanna (pauldhanna(AT)juno.com), Mar 06 2008