A185015 Characteristic function of 5.

0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 0

Author

Jason Kimberley, Sep 30 2011

Keywords

• nonn
• easy

Comments

Number of connected 2-regular (simple) graphs with girth exactly 5.

The Euler transformation of this sequence is A079998.

Links

• Index entries for linear recurrences with constant coefficients, signature (1).

Crossrefs

Characteristic function of g: A000007 (g=0), A063524 (g=1), A185012 (g=2), A185013 (g=3), A185014 (g=4), this sequence (g=5), A185016 (g=6), A185017 (g=7).

Programs

Python

def A185015(n): return int(n==5) # Chai Wah Wu, Feb 04 2022

Formula

a(n) = A185115(n) - A185116(n).