A128526 Number of 4-indecomposable (connected) graphs on n nodes.

1, 1, 1, 2, 6, 21, 112, 853, 111, 181, 323, 437, 717, 1198, 1606, 2454, 3782, 4997, 7245, 10543, 13711, 19092, 26612, 34076, 45948, 61930, 78154, 102654, 134670, 167688, 215496, 276480, 340080, 429030, 540246, 657162, 815994, 1011264, 1217712, 1491336, 1822920, 2174898, 2631618, 3178230, 3760086, 4501332, 5378868, 6314748, 7487964, 8863635

Offset

1,4

Comments

See A124593 for definition.

Links

Table of n, a(n) for n=1..50.

Formula

G.f.: x/((1-x)*(1-x^2)^2*(1-x^3)^8) + 1 - x^3 - 5*x^4 + 7*x^5 + 82*x^6 + 783*x^7 + 17*x^8 + 10*x^9.

Crossrefs

Cf. A126099, A128527, A128528

Sequence in context: A076324 A303032 A076325 * A076326 A076327 A128527

Adjacent sequences: A128523 A128524 A128525 * A128527 A128528 A128529

Keyword

nonn

Author

David Applegate and N. J. A. Sloane, Mar 07 2007

Status

approved