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Different Fiedler pencils with repetitions of degree n.
1

%I #11 Aug 23 2022 12:30:50

%S 1,6,37,254,1958,16910,162839,1738846,20469724,264061262,3710515665,

%T 56463372510,925339183634,16248435935342,304279525428443,

%U 6051490582876670,127336699707863032,2825520081496305262,65918580247670293685,1612619297571639402174

%N Different Fiedler pencils with repetitions of degree n.

%C In essence the self-convolution of A005189 (omitting the first 2 terms).

%H Poloni, Federico; Del Corso, Gianna M. <a href="https://doi.org/10.1016/j.laa.2017.06.042">Counting Fiedler pencils with repetitions</a>. Linear Algebra Appl. 532, 463-499 (2017), corollary 22.

%F a(n) = Sum_{g=1..n} A005189(1+g)*A005189(n-g+2).

%p A355957 := proc(d)

%p add(A005189(1+g)*A005189(d-g+2),g=1..d) ;

%p end proc:

%p seq(A355957(n),n=1..30) ;

%K nonn

%O 1,2

%A _R. J. Mathar_, Aug 23 2022