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A038526 Concatenation of prime factors of n-th Fibonacci number.

%I A038526 #18 Aug 17 2018 13:09:34
%S A038526 2,3,5,222,13,37,217,511,89,222233,233,1329,2561,3747,1597,2221719,
%T A038526 37113,351141,213421,89199,28657,2222233723,553001,233521,21753109,
%U A038526 31329281,514229,2225113161,5572417,37472207,28919801,15973571,513141961,22223331719107,731492221
%N A038526 Concatenation of prime factors of n-th Fibonacci number.
%H A038526 Alois P. Heinz, <a href="/A038526/b038526.txt">Table of n, a(n) for n = 3..380</a>
%F A038526 a(n) = A037276(A000045(n)). - _R. J. Mathar_, Oct 12 2007
%p A038526 A055642 := proc(n) if n =0 then 1 ; else ilog10(n)+1 ; fi ; end: catDigs := proc(L) local a,k,i ; a := 0 ; for i from 1 to nops(L) do a := a*10^A055642(L[i])+L[i] ; od ; end: A037276 := proc(n) local L,i,ifs,j ; if n = 1 then 0 else ifs := ifactors(n)[2] ; L := [] ; for i in ifs do for j from 1 to op(2,i) do L := [op(L),op(1,i)] ; od: od: catDigs(L) ; fi ; end: A038526 := proc(n) A037276(combinat[fibonacci](n)) ; end: seq(A038526(n),n=3..20) ; # _R. J. Mathar_, Oct 12 2007
%p A038526 # second Maple program:
%p A038526 F:= n-> (<<0|1>, <1|1>>^n)[1, 2]:
%p A038526 a:= n-> parse(cat(sort(map(i-> i[1]$i[2], ifactors(F(n))[2]))[])):
%p A038526 seq(a(n), n=3..40);  # _Alois P. Heinz_, Aug 17 2018
%K A038526 nonn,base
%O A038526 3,1
%A A038526 _Jeff Burch_
%E A038526 Edited by _Charles R Greathouse IV_, Apr 27 2010