A185014 - OEIS

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A185014

Characteristic function of four.

16

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

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OFFSET

0,1

COMMENTS

Number of connected 2-regular (simple) graphs with girth exactly 4.

The Euler transformation of this sequence is A121262.

LINKS

Table of n, a(n) for n=0..85.

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

FORMULA

a(n) = A185114(n) - A185115(n).

PROG

(Python)

def A185014(n): return int(n==4) # Chai Wah Wu, Feb 04 2022

CROSSREFS

Characteristic function of g: A000007 (g=0), A063524 (g=1), A185012 (g=2), A185013 (g=3), this sequence (g=4), A185015 (g=5), A185016 (g=6), A185017 (g=7).

Sequence in context: A011666 A011669 A023971 * A369036 A354948 A330551

Adjacent sequences: A185011 A185012 A185013 * A185015 A185016 A185017

KEYWORD

nonn,easy

AUTHOR

Jason Kimberley, Sep 30 2011

STATUS

approved