A185017 Characteristic function of 7.

0, 0, 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, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 0

Author

Jason Kimberley, Oct 14 2011

Keywords

• nonn
• easy

Comments

Number of connected 2-regular (simple) graphs with girth exactly 7.

The Euler transformation of this sequence is A082784.

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), A185015 (g=5), A185016 (g=6), this sequence (g=7).

Cf. A185117, A185118.

Programs

Python

def A185017(n): return int(n==7) # Chai Wah Wu, Feb 04 2022

Formula

a(n) = A185117(n) - A185118(n).