

A351782


a(n) = n2 if n is a multiple of 4, a(n) = n1 otherwise.


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OFFSET

1,3


COMMENTS

a(n) is the rank of the walk matrix of the Dynkin graph Dn, a tree obtained from the path of order n1 by adding a pendant edge at the second vertex. see Wang et al.


LINKS



FORMULA

a(n) = n  2 + sign(n mod 4).


MATHEMATICA

a[n_] := If[Divisible[n, 4], n  2, n  1]; Array[a, 70] (* Amiram Eldar, Mar 03 2022 *)


PROG

(PARI) a(n) = if (n%4, n1, n2);
(Python)


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



