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A305574 Number of primitive (1,1) pairs in the Fibonacci tree at depth 3n. 0

%I

%S 5,2,7,30,143,728,3876,21318,120175,690690,4032015,23841480,142498692,

%T 859515920,5225264024,31983672534,196947587823,1219199353190,

%U 7583142491925,47365474641870,296983176369495,1868545312633440,11793499763070480,74650344244967400

%N Number of primitive (1,1) pairs in the Fibonacci tree at depth 3n.

%D John Charles Saunders, Problems in Combinatorial and Analytic Number Theory, Ph. D. thesis, University of Waterloo, 2018.

%H Kevin G. Hare, and J. C. Saunders, <a href="https://arxiv.org/abs/1608.03522">On (a,b) Pairs in Random Fibonacci Sequences</a>, Arxiv preprint arXiv:1608.03522 [math.NT], February 2018.

%o (PARI) {a(n) = my(A); if( n<=1, 5*(n==1), A = O(x); for(k=1, n, A = x / (1 - A)^2); polcoeff(A, n))}; /* _Michael Somos_, Dec 10 2019 */

%K nonn

%O 1,1

%A _Jeffrey Shallit_, Jun 05 2018

%E More terms added and a(14) corrected by _Michael Somos_, Dec 10 2019

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Last modified September 22 03:54 EDT 2020. Contains 337289 sequences. (Running on oeis4.)