A238440 Expansion of 1/E(q/E(q)) where E(q) = Product_{n>=1} (1 - q^n).

1, 1, 3, 9, 27, 79, 229, 657, 1873, 5304, 14944, 41895, 116947, 325133, 900617, 2486183, 6841490, 18770754, 51358188, 140154540, 381540434, 1036261537, 2808328337, 7594958401, 20499680869, 55227373266, 148520150761, 398726637407, 1068701794158, 2859956501816, 7642086948143, 20391083977989, 54333644617311

Offset

0,3

Comments

What does this sequence count?

Links

Table of n, a(n) for n=0..32.

Formula

G.f.: 1/E(q/E(q)) where E(q) = Product_{n>=1} (1 - q^n).

Prog

(PARI) q = 'q + O('q^66);  Vec( 1/eta(q/eta(q)) )

Crossrefs

Cf. A109085: G.f. 1/E(q/E(q/E(q/E(q/E(q/E...))))).

Sequence in context: A266497 A291020 A282087 * A269578 A026289 A027129

Adjacent sequences: A238437 A238438 A238439 * A238441 A238442 A238443

Keyword

nonn

Author

Joerg Arndt, Feb 27 2014

Status

approved