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A050927 Number of directed multigraphs with loops on 3 nodes with n arcs. 4
1, 2, 10, 31, 90, 222, 520, 1090, 2180, 4090, 7356, 12660, 21105, 34020, 53460, 81891, 122826, 180510, 260746, 370370, 518518, 715870, 976170, 1315470, 1753975, 2314936, 3027224, 3923845, 5044920, 6436200, 8152542, 10255896 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

FORMULA

G.f.: (x^10+3*x^8+10*x^7+16*x^6+12*x^5+16*x^4+10*x^3+3*x^2+1) / ((1-x^3)^3*(1-x^2)^4*(1-x)^2).

CROSSREFS

Cf. A005993.

Sequence in context: A193008 A024456 A197452 * A197302 A011921 A103290

Adjacent sequences:  A050924 A050925 A050926 * A050928 A050929 A050930

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)eunet.rs), Dec 30 1999

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Last modified February 13 08:12 EST 2012. Contains 205451 sequences.