A128527 - OEIS

A128527

Number of 5-indecomposable (connected) graphs on n nodes.

1, 1, 1, 2, 6, 21, 112, 853, 11117, 261080, 3181, 6903, 16029, 37762, 60698, 136522, 295370, 617884, 1031444, 2148844, 4278884, 8230174, 13901726, 27183550, 50879126, 92491135, 155765543, 289049521, 515807289, 899791226, 1498906514, 2663076114, 4575392562, 7727941845, 12683646957, 21727344375, 36188012919, 59514326840, 96079635752, 159569603160

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

COMMENTS

See A124593 for definition.

LINKS

Table of n, a(n) for n=1..40.

FORMULA

G.f.: x/((1-x)*(1-x^2)^2*(1-x^3)^8*(1-x^4)^44) + 1 - x^3 - 5*x^4 - 37*x^5 + 38*x^6 + 651*x^7 + 10539*x^8 + 259303*x^9 + 548*x^10 + 416*x^11 + 286*x^12.

CROSSREFS

Cf. A126099, A128526, A128528

Sequence in context: A128526 A076326 A076327 * A076328 A128528 A001349

Adjacent sequences: A128524 A128525 A128526 * A128528 A128529 A128530

KEYWORD

nonn

AUTHOR

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

STATUS

approved