# New in *MathWorld* -- February
2007

### Wednesday February 28, 2007

- Graph Crossing Number (modified)

### Tuesday February 27, 2007

- Heawood Graph (modified)
- Petersen Graph (modified)

### Monday February 26, 2007

- Integer Sequence Primes (modified)
- Perrin Sequence (modified)
- Sylvester Matrix (modified)

### Sunday February 25, 2007

- Identity Graph (modified)

### Saturday February 24, 2007

- Dürer's Solid (modified)
- Escher's Solid (modified)
- Euler-Mascheroni Integrals (modified)
- Jessen's Orthogonal Icosahedron (modified)
- Spikey (modified)

### Monday February 19, 2007

- 2 (modified)
- Integer Sequence Primes (modified)
- Lucas Number (modified)
- Lucas Pseudoprime (modified)
- Perrin Sequence (modified)
- Tesseract (modified)
- Waring's Problem (modified)

### Saturday February 17, 2007

- 24-Cell (modified)
- Bellows Conjecture (modified)
- Eyeball Theorem (modified)
- Harmonic Number (modified)
- Integer Sequence Primes (modified)

### Monday February 5, 2007

- Integer Sequence Primes (modified)
- Perrin Sequence (modified)

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