%I #17 Jun 05 2017 16:16:40

%S 4,5,9,14,14,10,6,7,13,11,6,8,14,13,9,13,13,8,12,11,5,7,12,10,4,5,9,

%T 14,14,10,6,7,13,11,6,8,14,13,9,13,13,8,12,11,5,7,12,10,4,5,9,14,14,

%U 10,6,7,13,11,6,8,14,13,9,13,13,8,12,11,5,7,12,10,4,5,9,14,14,10,6,7,13,11,6,8

%N a(1)=4, a(2)=5, a(n) = sum of digits of a(n-1) + sum of digits of a(n-2), n>=3.

%C Digital sum analog in base 10 of the Fibonacci recurrence starting with 4,5.

%C The sequence is periodic from n=1 with period 24.

%H <a href="/index/Rec#order_23">Index entries for linear recurrences with constant coefficients</a>, signature (1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, 1).

%F a(n) = a(n-1) + a(n-2) - 9*(floor(a(n-1)/10)+floor(a(n-2)/10)).

%t a[n_] := a[n] = If[n <= 2, n + 3, Total@ IntegerDigits[a[n - 1]] + Total@ IntegerDigits[a[n - 2]]]; Array[a, 84] (* _Michael De Vlieger_, May 22 2017 *)

%Y Cf. A000285, A283428.

%K nonn,base

%O 1,1

%A _Enrique Navarrete_, May 21 2017