A144075 Duplicate of A008621.

1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21

Offset: 1

Author

Eric W. Weisstein, Sep 09 2008

Keywords

• dead

Links

• Eric Weisstein's World of Mathematics, Graph Thickness

Crossrefs

Cf. A002265, A128929.

Programs

Mathematica

Ceiling[(n+1)/4]

Formula

G.f.: x(1+x^3-x^4)/((1-x)^2(1+x)(1+x^2)). - R. J. Mathar, Sep 12 2008